diff --git a/accounts/admin.py b/accounts/admin.py
deleted file mode 100644
index 16c00b3..0000000
--- a/accounts/admin.py
+++ /dev/null
@@ -1,51 +0,0 @@
-from django.contrib import admin
-from django.contrib.auth.admin import UserAdmin as BaseUserAdmin
-
-from .forms import UserChangeForm, UserCreationForm
-from .models import Family, Member, User
-
-
-@admin.register(User)
-class UserAdmin(BaseUserAdmin):
-    add_form = UserCreationForm
-    form = UserChangeForm
-    model = User
-
-    list_display = ("email", "is_staff", "is_superuser", "is_active")
-    list_filter = ("is_staff", "is_superuser", "is_active", "groups")
-    search_fields = ("email",)
-    ordering = ("email",)
-
-    fieldsets = (
-        (None, {"fields": ("email", "password")}),
-        ("Permissions", {"fields": ("is_active", "is_staff", "is_superuser", "groups", "user_permissions")}),
-        ("Important dates", {"fields": ("last_login", "date_joined")}),
-    )
-    add_fieldsets = (
-        (None, {
-            "classes": ("wide",),
-            "fields": ("email", "usable_password", "password1", "password2"),
-        }),
-    )
-
-
-class MemberInline(admin.TabularInline):
-    model = Member
-    extra = 0
-    fields = ("first_name", "last_name", "date_of_birth", "is_guardian", "license_number")
-    show_change_link = True
-
-
-@admin.register(Member)
-class MemberAdmin(admin.ModelAdmin):
-    list_display = ("last_name", "first_name", "date_of_birth", "is_guardian", "license_number", "family", "user")
-    list_filter = ("is_guardian", "family")
-    search_fields = ("first_name", "last_name", "email", "license_number")
-    autocomplete_fields = ("user", "family")
-
-
-@admin.register(Family)
-class FamilyAdmin(admin.ModelAdmin):
-    list_display = ("name", "address")
-    search_fields = ("name",)
-    inlines = (MemberInline,)
diff --git a/accounts/apps.py b/accounts/apps.py
deleted file mode 100644
index 0cb51e6..0000000
--- a/accounts/apps.py
+++ /dev/null
@@ -1,6 +0,0 @@
-from django.apps import AppConfig
-
-
-class AccountsConfig(AppConfig):
-    default_auto_field = "django.db.models.BigAutoField"
-    name = "accounts"
diff --git a/accounts/forms.py b/accounts/forms.py
deleted file mode 100644
index 6bada4f..0000000
--- a/accounts/forms.py
+++ /dev/null
@@ -1,16 +0,0 @@
-from django.contrib.auth.forms import BaseUserCreationForm
-from django.contrib.auth.forms import UserChangeForm as BaseUserChangeForm
-
-from .models import User
-
-
-class UserCreationForm(BaseUserCreationForm):
-    class Meta(BaseUserCreationForm.Meta):
-        model = User
-        fields = ("email",)
-
-
-class UserChangeForm(BaseUserChangeForm):
-    class Meta(BaseUserChangeForm.Meta):
-        model = User
-        fields = "__all__"
diff --git a/accounts/models.py b/accounts/models.py
deleted file mode 100644
index 8b7e88e..0000000
--- a/accounts/models.py
+++ /dev/null
@@ -1,122 +0,0 @@
-from django.conf import settings
-from django.contrib.auth.models import AbstractBaseUser, PermissionsMixin
-from django.db import models
-from django.utils import timezone
-from phonenumber_field.modelfields import PhoneNumberField
-
-from .managers import UserManager
-
-
-class User(AbstractBaseUser, PermissionsMixin):
-    """Login identity. Only people who actually sign in get a User.
-
-    Personal/roster data lives on :class:`Member`; this model carries just the
-    authentication identity. ``PermissionsMixin`` provides ``is_superuser``,
-    ``groups`` and ``user_permissions`` (the basis for the access tiers).
-    """
-
-    email = models.EmailField(unique=True)
-    is_staff = models.BooleanField(
-        default=False,
-        help_text="Whether the user can log into the admin site.",
-    )
-    is_active = models.BooleanField(default=True)
-    date_joined = models.DateTimeField(default=timezone.now)
-
-    objects = UserManager()
-
-    USERNAME_FIELD = "email"
-    REQUIRED_FIELDS = []
-
-    def __str__(self):
-        return self.get_full_name()
-
-    def get_full_name(self):
-        member = getattr(self, "member", None)
-        if member is not None:
-            return f"{member.first_name} {member.last_name}".strip()
-        return self.email
-
-    def get_short_name(self):
-        member = getattr(self, "member", None)
-        if member is not None:
-            return member.first_name
-        return self.email
-
-
-class Family(models.Model):
-    """A household grouping members together."""
-
-    name = models.CharField(max_length=150, help_text='e.g. "The Smiths"')
-    address = models.CharField(max_length=255, blank=True)
-
-    class Meta:
-        ordering = ["name"]
-        verbose_name_plural = "families"
-
-    def __str__(self):
-        return self.name
-
-
-class Member(models.Model):
-    """A person in the club. May or may not have a login (:attr:`user`).
-
-    Family relationships are modelled by membership in a :class:`Family`:
-    guardians (``is_guardian=True``) look after the other members of the same
-    family (the dependents).
-    """
-
-    user = models.OneToOneField(
-        settings.AUTH_USER_MODEL,
-        on_delete=models.SET_NULL,
-        null=True,
-        blank=True,
-        related_name="member",
-    )
-
-    first_name = models.CharField(max_length=150)
-    last_name = models.CharField(max_length=150)
-    # Contact email — optional. Children may have none; a login email lives on User.
-    # Use `contact_email` to read it with a fallback to the linked user's login email.
-    email = models.EmailField(blank=True)
-    phone = PhoneNumberField(blank=True)
-    emergency_phone = PhoneNumberField(blank=True)
-    license_number = models.CharField(max_length=50, blank=True)
-    date_of_birth = models.DateField()
-
-    family = models.ForeignKey(
-        Family,
-        on_delete=models.SET_NULL,
-        null=True,
-        blank=True,
-        related_name="members",
-    )
-    is_guardian = models.BooleanField(
-        default=False,
-        help_text="Whether this member is a parent/guardian in their family.",
-    )
-
-    class Meta:
-        ordering = ["last_name", "first_name"]
-
-    def __str__(self):
-        return f"{self.first_name} {self.last_name}"
-
-    @property
-    def contact_email(self):
-        """Best email to reach this member: own contact email, else login email."""
-        return self.email or (self.user.email if self.user_id else "")
-
-    @property
-    def guardians(self):
-        """Members of my family who look after me (only if I'm a dependent)."""
-        if self.is_guardian or self.family_id is None:
-            return Member.objects.none()
-        return self.family.members.filter(is_guardian=True)
-
-    @property
-    def dependents(self):
-        """Members of my family I look after (only if I'm a guardian)."""
-        if not self.is_guardian or self.family_id is None:
-            return Member.objects.none()
-        return self.family.members.filter(is_guardian=False)
diff --git a/accounts/tests.py b/accounts/tests.py
deleted file mode 100644
index 46a01d4..0000000
--- a/accounts/tests.py
+++ /dev/null
@@ -1,109 +0,0 @@
-from django.core.exceptions import ValidationError
-from django.test import TestCase
-
-from .models import Family, Member, User
-
-
-class UserManagerTests(TestCase):
-    def test_create_user_with_email(self):
-        user = User.objects.create_user(email="Parent@Example.com", password="pw")
-        self.assertEqual(user.email, "Parent@example.com")  # domain normalized
-        self.assertTrue(user.check_password("pw"))
-        self.assertFalse(user.is_staff)
-        self.assertFalse(user.is_superuser)
-
-    def test_create_superuser(self):
-        admin = User.objects.create_superuser(email="admin@example.com", password="pw")
-        self.assertTrue(admin.is_staff)
-        self.assertTrue(admin.is_superuser)
-
-    def test_create_user_requires_email(self):
-        with self.assertRaises(ValueError):
-            User.objects.create_user(email="", password="pw")
-
-    def test_create_superuser_rejects_non_superuser_flag(self):
-        with self.assertRaises(ValueError):
-            User.objects.create_superuser(email="a@b.com", password="pw", is_superuser=False)
-
-
-class MemberTests(TestCase):
-    def test_member_without_login_or_optional_fields(self):
-        member = Member.objects.create(
-            first_name="Kid",
-            last_name="Smith",
-            date_of_birth="2015-05-01",
-        )
-        self.assertIsNone(member.user)
-        self.assertEqual(member.email, "")
-        self.assertEqual(member.phone, "")
-        self.assertEqual(member.license_number, "")
-
-    def test_valid_phone_accepted(self):
-        member = Member(
-            first_name="Ann",
-            last_name="Smith",
-            date_of_birth="1980-01-01",
-            phone="+32470123456",
-        )
-        member.full_clean()  # should not raise
-
-    def test_invalid_phone_rejected(self):
-        member = Member(
-            first_name="Ann",
-            last_name="Smith",
-            date_of_birth="1980-01-01",
-            phone="not-a-number",
-        )
-        with self.assertRaises(ValidationError):
-            member.full_clean()
-
-    def test_contact_email_prefers_own_then_login(self):
-        # No own email, no user -> empty.
-        member = Member.objects.create(
-            first_name="Kid", last_name="Smith", date_of_birth="2015-05-01"
-        )
-        self.assertEqual(member.contact_email, "")
-
-        # Linked user, no own email -> falls back to login email.
-        member.user = User.objects.create_user(email="login@example.com", password="pw")
-        member.save()
-        self.assertEqual(member.contact_email, "login@example.com")
-
-        # Own contact email wins over login email.
-        member.email = "contact@example.com"
-        self.assertEqual(member.contact_email, "contact@example.com")
-
-
-class FamilyTests(TestCase):
-    def setUp(self):
-        self.family = Family.objects.create(name="The Smiths")
-        self.parent = Member.objects.create(
-            first_name="Ann", last_name="Smith", date_of_birth="1980-01-01",
-            family=self.family, is_guardian=True,
-        )
-        self.child = Member.objects.create(
-            first_name="Kid", last_name="Smith", date_of_birth="2015-05-01",
-            family=self.family, is_guardian=False,
-        )
-
-    def test_family_groups_members(self):
-        self.assertEqual(self.family.members.count(), 2)
-
-    def test_child_guardians_are_family_guardians(self):
-        self.assertIn(self.parent, self.child.guardians)
-        self.assertNotIn(self.child, self.child.guardians)
-
-    def test_guardian_dependents_are_family_non_guardians(self):
-        self.assertIn(self.child, self.parent.dependents)
-        self.assertNotIn(self.parent, self.parent.dependents)
-
-    def test_guardian_has_no_guardians_and_child_has_no_dependents(self):
-        self.assertEqual(list(self.parent.guardians), [])
-        self.assertEqual(list(self.child.dependents), [])
-
-    def test_member_without_family_has_no_relations(self):
-        loner = Member.objects.create(
-            first_name="Solo", last_name="Jones", date_of_birth="1990-01-01"
-        )
-        self.assertEqual(list(loner.guardians), [])
-        self.assertEqual(list(loner.dependents), [])
diff --git a/accounts/__init__.py b/authentication/__init__.py
similarity index 100%
rename from accounts/__init__.py
rename to authentication/__init__.py
diff --git a/authentication/admin.py b/authentication/admin.py
new file mode 100644
index 0000000..8c38f3f
--- /dev/null
+++ b/authentication/admin.py
@@ -0,0 +1,3 @@
+from django.contrib import admin
+
+# Register your models here.
diff --git a/authentication/apps.py b/authentication/apps.py
new file mode 100644
index 0000000..9635c9d
--- /dev/null
+++ b/authentication/apps.py
@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class AuthenticationConfig(AppConfig):
+    name = 'authentication'
diff --git a/accounts/managers.py b/authentication/managers.py
similarity index 100%
rename from accounts/managers.py
rename to authentication/managers.py
diff --git a/accounts/migrations/0001_initial.py b/authentication/migrations/0001_initial.py
similarity index 51%
rename from accounts/migrations/0001_initial.py
rename to authentication/migrations/0001_initial.py
index 0b39cf3..5e98af2 100644
--- a/accounts/migrations/0001_initial.py
+++ b/authentication/migrations/0001_initial.py
@@ -1,9 +1,9 @@
-# Generated by Django 6.0.6 on 2026-07-01 22:16
+# Generated by Django 6.0.6 on 2026-07-02 07:33
 
-import accounts.managers
+import authentication.managers
 import django.db.models.deletion
-import django.utils.timezone
 import phonenumber_field.modelfields
+import uuid
 from django.conf import settings
 from django.db import migrations, models
 
@@ -20,11 +20,11 @@ class Migration(migrations.Migration):
         migrations.CreateModel(
             name='Family',
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('name', models.CharField(help_text='e.g. "The Smiths"', max_length=150)),
-                ('address', models.CharField(blank=True, max_length=255)),
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('name', models.CharField(max_length=255)),
             ],
             options={
+                'verbose_name': 'family',
                 'verbose_name_plural': 'families',
                 'ordering': ['name'],
             },
@@ -32,41 +32,63 @@ class Migration(migrations.Migration):
         migrations.CreateModel(
             name='User',
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                 ('password', models.CharField(max_length=128, verbose_name='password')),
                 ('last_login', models.DateTimeField(blank=True, null=True, verbose_name='last login')),
                 ('is_superuser', models.BooleanField(default=False, help_text='Designates that this user has all permissions without explicitly assigning them.', verbose_name='superuser status')),
-                ('email', models.EmailField(max_length=254, unique=True)),
-                ('is_staff', models.BooleanField(default=False, help_text='Whether the user can log into the admin site.')),
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('email', models.EmailField(db_index=True, max_length=254, unique=True)),
+                ('is_staff', models.BooleanField(default=False)),
                 ('is_active', models.BooleanField(default=True)),
-                ('date_joined', models.DateTimeField(default=django.utils.timezone.now)),
                 ('groups', models.ManyToManyField(blank=True, help_text='The groups this user belongs to. A user will get all permissions granted to each of their groups.', related_name='user_set', related_query_name='user', to='auth.group', verbose_name='groups')),
                 ('user_permissions', models.ManyToManyField(blank=True, help_text='Specific permissions for this user.', related_name='user_set', related_query_name='user', to='auth.permission', verbose_name='user permissions')),
             ],
             options={
-                'abstract': False,
+                'verbose_name': 'user',
+                'verbose_name_plural': 'users',
+                'ordering': ['email'],
             },
             managers=[
-                ('objects', accounts.managers.UserManager()),
+                ('objects', authentication.managers.UserManager()),
             ],
         ),
         migrations.CreateModel(
             name='Member',
             fields=[
-                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
                 ('first_name', models.CharField(max_length=150)),
                 ('last_name', models.CharField(max_length=150)),
+                ('date_of_birth', models.DateField(blank=True, null=True)),
                 ('email', models.EmailField(blank=True, max_length=254)),
-                ('phone', phonenumber_field.modelfields.PhoneNumberField(blank=True, max_length=128, region=None)),
-                ('emergency_phone', phonenumber_field.modelfields.PhoneNumberField(blank=True, max_length=128, region=None)),
-                ('license_number', models.CharField(blank=True, max_length=50)),
-                ('date_of_birth', models.DateField()),
-                ('is_guardian', models.BooleanField(default=False, help_text='Whether this member is a parent/guardian in their family.')),
-                ('family', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='members', to='accounts.family')),
+                ('phone', phonenumber_field.modelfields.PhoneNumberField(blank=True, max_length=128, null=True, region=None)),
+                ('emergency_phone', phonenumber_field.modelfields.PhoneNumberField(blank=True, max_length=128, null=True, region=None)),
                 ('user', models.OneToOneField(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='member', to=settings.AUTH_USER_MODEL)),
             ],
             options={
+                'verbose_name': 'member',
+                'verbose_name_plural': 'members',
                 'ordering': ['last_name', 'first_name'],
             },
         ),
+        migrations.CreateModel(
+            name='FamilyMembership',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('role', models.CharField(choices=[('parent', 'parent'), ('child', 'child'), ('guardian', 'guardian'), ('other', 'other')], default='parent', max_length=255)),
+                ('family', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='memberships', to='authentication.family')),
+                ('member', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='family_memberships', to='authentication.member')),
+            ],
+            options={
+                'verbose_name': 'family membership',
+                'verbose_name_plural': 'family memberships',
+                'ordering': ['family', 'role', 'member__last_name', 'member__first_name'],
+            },
+        ),
+        migrations.AddIndex(
+            model_name='member',
+            index=models.Index(fields=['last_name', 'first_name'], name='authenticat_last_na_0a0eca_idx'),
+        ),
+        migrations.AlterUniqueTogether(
+            name='familymembership',
+            unique_together={('family', 'member')},
+        ),
     ]
diff --git a/accounts/migrations/__init__.py b/authentication/migrations/__init__.py
similarity index 100%
rename from accounts/migrations/__init__.py
rename to authentication/migrations/__init__.py
diff --git a/authentication/models.py b/authentication/models.py
new file mode 100644
index 0000000..29c9fab
--- /dev/null
+++ b/authentication/models.py
@@ -0,0 +1,128 @@
+import uuid
+
+from django.conf import settings
+from django.contrib.auth.base_user import AbstractBaseUser
+from django.contrib.auth.models import PermissionsMixin
+from django.db import models
+from django.utils.translation import gettext_lazy as _
+from phonenumber_field.modelfields import PhoneNumberField
+
+from clubmanager.base import UUIDModel
+
+from .managers import UserManager
+
+
+class User(AbstractBaseUser, PermissionsMixin):
+    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    email = models.EmailField(unique=True, db_index=True)
+
+    is_staff = models.BooleanField(default=False)
+    is_active = models.BooleanField(default=True)
+
+    objects = UserManager()
+
+    USERNAME_FIELD = "email"
+    REQUIRED_FIELDS = []
+
+    class Meta:
+        verbose_name = _("user")
+        verbose_name_plural = _("users")
+        ordering = ["email"]
+
+    def __str__(self):
+        return self.get_full_name()
+
+    def get_full_name(self):
+        member = getattr(self, "member", None)
+        if member is not None:
+            return member.get_full_name()
+        return self.email
+
+    def get_short_name(self):
+        member = getattr(self, "member", None)
+        if member is not None:
+            return member.get_short_name()
+        return self.email
+
+
+class Family(UUIDModel):
+    name = models.CharField(max_length=255)
+
+    class Meta:
+        verbose_name = _("family")
+        verbose_name_plural = _("families")
+        ordering = ["name"]
+
+    def __str__(self):
+        return self.name
+
+    @property
+    def guardians(self):
+        return Member.objects.filter(
+            family_memberships__family=self,
+            family_memberships__role__in=[FamilyMembership.FamilyRole.PARENT, FamilyMembership.FamilyRole.GUARDIAN],
+        )
+
+    @property
+    def children(self):
+        return Member.objects.filter(
+            family_memberships__family=self,
+            family_memberships__role=FamilyMembership.FamilyRole.CHILD,
+        )
+
+
+class Member(UUIDModel):
+    user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, related_name="member", null=True, blank=True)
+
+    first_name = models.CharField(max_length=150)
+    last_name = models.CharField(max_length=150)
+
+    date_of_birth = models.DateField(null=True, blank=True)
+
+    email = models.EmailField(blank=True)
+    phone = PhoneNumberField(null=True, blank=True)
+    emergency_phone = PhoneNumberField(null=True, blank=True)
+
+    class Meta:
+        verbose_name = _("member")
+        verbose_name_plural = _("members")
+        ordering = ["last_name", "first_name"]
+        indexes = [models.Index(fields=["last_name", "first_name"])]
+
+    def __str__(self):
+        return f"{self.first_name} {self.last_name}"
+
+    def get_full_name(self):
+        return f"{self.first_name} {self.last_name}".strip()
+
+    def get_short_name(self):
+        return self.first_name
+
+    @property
+    def guardians(self):
+        return Member.objects.filter(
+            family_memberships__role__in=[FamilyMembership.FamilyRole.PARENT, FamilyMembership.FamilyRole.GUARDIAN],
+            family_memberships__family__memberships__member=self,
+            family_memberships__family__memberships__role=FamilyMembership.FamilyRole.CHILD,
+        ).distinct()
+
+
+class FamilyMembership(models.Model):
+    class FamilyRole(models.TextChoices):
+        PARENT = "parent", _("parent")
+        CHILD = "child", _("child")
+        GUARDIAN = "guardian", _("guardian")
+        OTHER = "other", _("other")
+
+    family = models.ForeignKey(Family, on_delete=models.CASCADE, related_name="memberships")
+    member = models.ForeignKey(Member, on_delete=models.CASCADE, related_name="family_memberships")
+    role = models.CharField(max_length=255, choices=FamilyRole.choices, default=FamilyRole.PARENT)
+
+    class Meta:
+        verbose_name = _("family membership")
+        verbose_name_plural = _("family memberships")
+        ordering = ["family", "role", "member__last_name", "member__first_name"]
+        unique_together = ("family", "member")
+
+    def __str__(self):
+        return f"{self.family} - {self.member} ({self.get_role_display()})"
diff --git a/authentication/tests.py b/authentication/tests.py
new file mode 100644
index 0000000..431dd9f
--- /dev/null
+++ b/authentication/tests.py
@@ -0,0 +1,234 @@
+import uuid
+
+from django.contrib.auth import get_user_model
+from django.db import IntegrityError
+from django.db.models import SET_NULL
+from django.test import TestCase
+
+from authentication.models import Family, FamilyMembership, Member
+
+User = get_user_model()
+
+
+class UserManagerTests(TestCase):
+    def test_create_user_defaults(self):
+        user = User.objects.create_user(email="alice@example.com", password="secret123")
+
+        self.assertEqual(user.email, "alice@example.com")
+        self.assertTrue(user.check_password("secret123"))
+        self.assertFalse(user.is_staff)
+        self.assertFalse(user.is_superuser)
+        self.assertTrue(user.is_active)
+
+    def test_create_user_requires_email(self):
+        with self.assertRaises(ValueError):
+            User.objects.create_user(email="", password="secret123")
+
+    def test_create_user_normalizes_email_domain(self):
+        # BaseUserManager lowercases the domain part of the address.
+        user = User.objects.create_user(email="Bob@Example.COM", password="secret123")
+
+        self.assertEqual(user.email, "Bob@example.com")
+
+    def test_create_user_password_is_hashed(self):
+        user = User.objects.create_user(email="carol@example.com", password="secret123")
+
+        self.assertNotEqual(user.password, "secret123")
+
+    def test_create_user_without_password_is_unusable(self):
+        user = User.objects.create_user(email="dave@example.com")
+
+        self.assertFalse(user.has_usable_password())
+
+    def test_create_superuser_defaults(self):
+        admin = User.objects.create_superuser(email="admin@example.com", password="secret123")
+
+        self.assertTrue(admin.is_staff)
+        self.assertTrue(admin.is_superuser)
+        self.assertTrue(admin.is_active)
+
+    def test_create_superuser_rejects_non_staff(self):
+        with self.assertRaises(ValueError):
+            User.objects.create_superuser(email="admin@example.com", password="x", is_staff=False)
+
+    def test_create_superuser_rejects_non_superuser(self):
+        with self.assertRaises(ValueError):
+            User.objects.create_superuser(email="admin@example.com", password="x", is_superuser=False)
+
+
+class UserModelTests(TestCase):
+    def test_email_is_username_field(self):
+        self.assertEqual(User.USERNAME_FIELD, "email")
+        self.assertEqual(User.REQUIRED_FIELDS, [])
+
+    def test_email_is_unique(self):
+        User.objects.create_user(email="dup@example.com", password="x")
+        with self.assertRaises(IntegrityError):
+            User.objects.create_user(email="dup@example.com", password="y")
+
+    def test_pk_is_uuid(self):
+        user = User.objects.create_user(email="uuid@example.com", password="x")
+        self.assertIsInstance(user.pk, uuid.UUID)
+
+    def test_str_and_names_fall_back_to_email_without_member(self):
+        user = User.objects.create_user(email="lonely@example.com", password="x")
+
+        self.assertEqual(str(user), "lonely@example.com")
+        self.assertEqual(user.get_full_name(), "lonely@example.com")
+        self.assertEqual(user.get_short_name(), "lonely@example.com")
+
+    def test_str_and_names_use_linked_member(self):
+        user = User.objects.create_user(email="linked@example.com", password="x")
+        Member.objects.create(user=user, first_name="Jane", last_name="Doe")
+
+        # Re-fetch so the reverse OneToOne relation is resolved from the DB.
+        user = User.objects.get(pk=user.pk)
+
+        self.assertEqual(str(user), "Jane Doe")
+        self.assertEqual(user.get_full_name(), "Jane Doe")
+        self.assertEqual(user.get_short_name(), "Jane")
+
+
+class MemberModelTests(TestCase):
+    def test_str_and_name_helpers(self):
+        member = Member.objects.create(first_name="John", last_name="Smith")
+
+        self.assertEqual(str(member), "John Smith")
+        self.assertEqual(member.get_full_name(), "John Smith")
+        self.assertEqual(member.get_short_name(), "John")
+
+    def test_get_full_name_strips_when_partial(self):
+        member = Member.objects.create(first_name="Cher", last_name="")
+        self.assertEqual(member.get_full_name(), "Cher")
+
+    def test_member_can_exist_without_user(self):
+        member = Member.objects.create(first_name="No", last_name="Login")
+        self.assertIsNone(member.user)
+
+    def test_deleting_user_nulls_member_but_keeps_it(self):
+        user = User.objects.create_user(email="temp@example.com", password="x")
+        member = Member.objects.create(user=user, first_name="Keep", last_name="Me")
+
+        # OneToOneField uses on_delete=SET_NULL.
+        field = Member._meta.get_field("user")
+        self.assertIs(field.remote_field.on_delete, SET_NULL)
+
+        user.delete()
+        member.refresh_from_db()
+        self.assertIsNone(member.user)
+        self.assertTrue(Member.objects.filter(pk=member.pk).exists())
+
+    def test_user_member_is_one_to_one(self):
+        user = User.objects.create_user(email="once@example.com", password="x")
+        Member.objects.create(user=user, first_name="First", last_name="Member")
+
+        with self.assertRaises(IntegrityError):
+            Member.objects.create(user=user, first_name="Second", last_name="Member")
+
+
+class FamilyModelTests(TestCase):
+    def setUp(self):
+        self.family = Family.objects.create(name="The Smiths")
+        self.parent = Member.objects.create(first_name="Pat", last_name="Smith")
+        self.guardian = Member.objects.create(first_name="Gale", last_name="Smith")
+        self.child = Member.objects.create(first_name="Kim", last_name="Smith")
+        self.other = Member.objects.create(first_name="Ola", last_name="Smith")
+
+        FamilyMembership.objects.create(family=self.family, member=self.parent, role=FamilyMembership.FamilyRole.PARENT)
+        FamilyMembership.objects.create(family=self.family, member=self.guardian, role=FamilyMembership.FamilyRole.GUARDIAN)
+        FamilyMembership.objects.create(family=self.family, member=self.child, role=FamilyMembership.FamilyRole.CHILD)
+        FamilyMembership.objects.create(family=self.family, member=self.other, role=FamilyMembership.FamilyRole.OTHER)
+
+    def test_str(self):
+        self.assertEqual(str(self.family), "The Smiths")
+
+    def test_guardians_include_parents_and_guardians_only(self):
+        guardians = set(self.family.guardians)
+        self.assertEqual(guardians, {self.parent, self.guardian})
+
+    def test_children_include_children_only(self):
+        children = list(self.family.children)
+        self.assertEqual(children, [self.child])
+
+    def test_guardians_are_scoped_to_the_family(self):
+        other_family = Family.objects.create(name="The Joneses")
+        outsider = Member.objects.create(first_name="Out", last_name="Sider")
+        FamilyMembership.objects.create(family=other_family, member=outsider, role=FamilyMembership.FamilyRole.PARENT)
+
+        self.assertNotIn(outsider, set(self.family.guardians))
+
+
+class MemberGuardiansTests(TestCase):
+    def test_guardians_of_a_child_are_family_parents_and_guardians(self):
+        family = Family.objects.create(name="The Does")
+        mum = Member.objects.create(first_name="Mary", last_name="Doe")
+        legal = Member.objects.create(first_name="Lee", last_name="Doe")
+        kid = Member.objects.create(first_name="Kit", last_name="Doe")
+
+        FamilyMembership.objects.create(family=family, member=mum, role=FamilyMembership.FamilyRole.PARENT)
+        FamilyMembership.objects.create(family=family, member=legal, role=FamilyMembership.FamilyRole.GUARDIAN)
+        FamilyMembership.objects.create(family=family, member=kid, role=FamilyMembership.FamilyRole.CHILD)
+
+        self.assertEqual(set(kid.guardians), {mum, legal})
+
+    def test_guardians_empty_for_a_parent(self):
+        family = Family.objects.create(name="The Roes")
+        parent = Member.objects.create(first_name="Ray", last_name="Roe")
+        kid = Member.objects.create(first_name="Ren", last_name="Roe")
+
+        FamilyMembership.objects.create(family=family, member=parent, role=FamilyMembership.FamilyRole.PARENT)
+        FamilyMembership.objects.create(family=family, member=kid, role=FamilyMembership.FamilyRole.CHILD)
+
+        self.assertEqual(list(parent.guardians), [])
+
+    def test_guardians_do_not_leak_across_families(self):
+        family_a = Family.objects.create(name="Family A")
+        family_b = Family.objects.create(name="Family B")
+        parent_a = Member.objects.create(first_name="Ann", last_name="A")
+        parent_b = Member.objects.create(first_name="Ben", last_name="B")
+        kid = Member.objects.create(first_name="Cody", last_name="A")
+
+        FamilyMembership.objects.create(family=family_a, member=parent_a, role=FamilyMembership.FamilyRole.PARENT)
+        FamilyMembership.objects.create(family=family_a, member=kid, role=FamilyMembership.FamilyRole.CHILD)
+        # parent_b belongs to a different family and must not appear as kid's guardian.
+        FamilyMembership.objects.create(family=family_b, member=parent_b, role=FamilyMembership.FamilyRole.PARENT)
+
+        self.assertEqual(set(kid.guardians), {parent_a})
+
+
+class FamilyMembershipModelTests(TestCase):
+    def test_default_role_is_parent(self):
+        family = Family.objects.create(name="Fam")
+        member = Member.objects.create(first_name="D", last_name="Efault")
+        membership = FamilyMembership.objects.create(family=family, member=member)
+
+        self.assertEqual(membership.role, FamilyMembership.FamilyRole.PARENT)
+
+    def test_member_unique_per_family(self):
+        family = Family.objects.create(name="Fam")
+        member = Member.objects.create(first_name="Solo", last_name="Once")
+        FamilyMembership.objects.create(family=family, member=member, role=FamilyMembership.FamilyRole.PARENT)
+
+        with self.assertRaises(IntegrityError):
+            FamilyMembership.objects.create(family=family, member=member, role=FamilyMembership.FamilyRole.CHILD)
+
+    def test_same_member_can_join_multiple_families(self):
+        member = Member.objects.create(first_name="Multi", last_name="Fam")
+        family_a = Family.objects.create(name="A")
+        family_b = Family.objects.create(name="B")
+
+        FamilyMembership.objects.create(family=family_a, member=member, role=FamilyMembership.FamilyRole.CHILD)
+        FamilyMembership.objects.create(family=family_b, member=member, role=FamilyMembership.FamilyRole.PARENT)
+
+        self.assertEqual(member.family_memberships.count(), 2)
+
+    def test_deleting_family_cascades_to_memberships(self):
+        family = Family.objects.create(name="Doomed")
+        member = Member.objects.create(first_name="Cas", last_name="Cade")
+        FamilyMembership.objects.create(family=family, member=member)
+
+        family.delete()
+
+        self.assertFalse(FamilyMembership.objects.exists())
+        # The member itself survives; only the membership is removed.
+        self.assertTrue(Member.objects.filter(pk=member.pk).exists())
diff --git a/authentication/views.py b/authentication/views.py
new file mode 100644
index 0000000..91ea44a
--- /dev/null
+++ b/authentication/views.py
@@ -0,0 +1,3 @@
+from django.shortcuts import render
+
+# Create your views here.
diff --git a/club/__init__.py b/club/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/club/admin.py b/club/admin.py
new file mode 100644
index 0000000..8c38f3f
--- /dev/null
+++ b/club/admin.py
@@ -0,0 +1,3 @@
+from django.contrib import admin
+
+# Register your models here.
diff --git a/club/apps.py b/club/apps.py
new file mode 100644
index 0000000..67bff61
--- /dev/null
+++ b/club/apps.py
@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class ClubConfig(AppConfig):
+    name = 'club'
diff --git a/club/migrations/__init__.py b/club/migrations/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/club/models.py b/club/models.py
new file mode 100644
index 0000000..c7ab82a
--- /dev/null
+++ b/club/models.py
@@ -0,0 +1,20 @@
+from django.contrib.auth.base_user import AbstractBaseUser
+from django.db import models
+from django.utils.translation import gettext_lazy as _
+
+from clubmanager.base import ClubScopedModel, UUIDModel
+
+
+class Club(UUIDModel):
+    name = models.CharField(max_length=255)
+
+    class Meta:
+        verbose_name = _("club")
+        verbose_name_plural = _("clubs")
+        ordering = ["name"]
+
+    def __str__(self):
+        return self.name
+
+
+class ClubMembership(UUIDModel): ...
diff --git a/club/tests.py b/club/tests.py
new file mode 100644
index 0000000..7ce503c
--- /dev/null
+++ b/club/tests.py
@@ -0,0 +1,3 @@
+from django.test import TestCase
+
+# Create your tests here.
diff --git a/club/views.py b/club/views.py
new file mode 100644
index 0000000..91ea44a
--- /dev/null
+++ b/club/views.py
@@ -0,0 +1,3 @@
+from django.shortcuts import render
+
+# Create your views here.
diff --git a/clubmanager/base.py b/clubmanager/base.py
new file mode 100644
index 0000000..8b1346a
--- /dev/null
+++ b/clubmanager/base.py
@@ -0,0 +1,21 @@
+import uuid
+
+from django.db import models
+
+
+class UUIDModel(models.Model):
+    """Abstract base class giving every model a UUID primary key"""
+
+    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+
+    class Meta:
+        abstract = True
+
+
+class ClubScopedModel(UUIDModel):
+    """Abstract base for entities owned by a single club (tenant root)."""
+
+    club = models.ForeignKey("club.Club", on_delete=models.CASCADE, related_name="%(class)ss")
+
+    class Meta:
+        abstract = True
diff --git a/clubmanager/settings.py b/clubmanager/settings.py
index 418b78f..d55bd6c 100644
--- a/clubmanager/settings.py
+++ b/clubmanager/settings.py
@@ -44,11 +44,10 @@ INSTALLED_APPS = [
     "django.contrib.messages",
     "django.contrib.staticfiles",
     "phonenumber_field",
-    "accounts",
+    "club.apps.ClubConfig",
+    "authentication.apps.AuthenticationConfig",
 ]
 
-AUTH_USER_MODEL = "accounts.User"
-
 MIDDLEWARE = [
     "django.middleware.security.SecurityMiddleware",
     "django.contrib.sessions.middleware.SessionMiddleware",
@@ -61,6 +60,8 @@ MIDDLEWARE = [
 
 ROOT_URLCONF = "clubmanager.urls"
 
+AUTH_USER_MODEL = "authentication.User"
+
 TEMPLATES = [
     {
         "BACKEND": "django.template.backends.django.DjangoTemplates",