diff --git a/calsocial/__init__.py b/calsocial/__init__.py
index f2085bd..e4c03c0 100644
--- a/calsocial/__init__.py
+++ b/calsocial/__init__.py
@@ -29,6 +29,7 @@ from sqlalchemy.orm.exc import NoResultFound, MultipleResultsFound
 
 from calsocial.account import AccountBlueprint
 from calsocial.cache import CachedSessionInterface, cache
+from calsocial.group import GroupBlueprint
 from calsocial.utils import RoutedMixin
 
 
@@ -109,6 +110,7 @@ class CalendarSocialApp(Flask, RoutedMixin):
         RoutedMixin.register_routes(self)
 
         AccountBlueprint().init_app(self, '/accounts/')
+        GroupBlueprint().init_app(self, '/groups/')
 
         self.before_request(self.goto_first_steps)
 
diff --git a/calsocial/forms.py b/calsocial/forms.py
index 23150c0..68aaebb 100644
--- a/calsocial/forms.py
+++ b/calsocial/forms.py
@@ -28,7 +28,8 @@ from wtforms.ext.dateutil.fields import DateTimeField
 from wtforms.validators import DataRequired, Email, StopValidation, ValidationError
 from wtforms.widgets import TextArea
 
-from calsocial.models import EventVisibility, EVENT_VISIBILITY_TRANSLATIONS
+from calsocial.models import EventVisibility, EVENT_VISIBILITY_TRANSLATIONS, GroupVisibility, \
+    GROUP_VISIBILITY_TRANSLATIONS
 
 
 class UsernameAvailable:  # pylint: disable=too-few-public-methods
@@ -411,3 +412,43 @@ class ProfileForm(FlaskForm):
         self.builtin_avatar.choices = [(name, name)
                                        for name in current_app.config['BUILTIN_AVATARS']]
         self.profile = profile
+
+
+class HandleAvailable:  # pylint: disable=too-few-public-methods
+    """Checks if a group handle is available
+    """
+
+    def __init__(self, message=None):
+        self.message = message
+
+    def __call__(self, form, field):
+        from sqlalchemy.orm.exc import NoResultFound
+
+        from calsocial.models import Group
+
+        # If there is no data, we don’t raise an error; it’s not the task of this validator to
+        # check the validity of the username
+        if not field.data:
+            return
+
+        try:
+            Group.query.filter(Group.handle == field.data).one()
+        except NoResultFound:
+            return
+
+        if self.message is None:
+            message = field.gettext('This group handle is not available')
+        else:
+            message = self.message
+
+        field.errors[:] = []
+        raise StopValidation(message)
+
+
+class GroupForm(FlaskForm):
+    """Form for editing a group
+    """
+
+    handle = StringField(label=_('Handle'), validators=[DataRequired(), HandleAvailable()])
+    display_name = StringField(label=_('Display name'))
+    visibility = EnumField(GroupVisibility, GROUP_VISIBILITY_TRANSLATIONS, label=_('Visibility'))
diff --git a/calsocial/group.py b/calsocial/group.py
new file mode 100644
index 0000000..66744e0
--- /dev/null
+++ b/calsocial/group.py
@@ -0,0 +1,100 @@
+# Calendar.social
+# Copyright (C) 2018  Gergely Polonkai
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""Group related endpoints for Calendar.social
+"""
+
+from flask import Blueprint, abort, redirect, render_template, url_for
+from flask_security import current_user, login_required
+
+from calsocial.utils import RoutedMixin
+
+
+class GroupBlueprint(Blueprint, RoutedMixin):
+    def __init__(self):
+        Blueprint.__init__(self, 'group', __name__)
+
+        self.app = None
+
+        RoutedMixin.register_routes(self)
+
+    def init_app(self, app, url_prefix=None):
+        """Initialise the blueprint, registering it with ``app``.
+        """
+
+        self.app = app
+
+        app.register_blueprint(self, url_prefix=url_prefix)
+
+    @staticmethod
+    @RoutedMixin.route('/')
+    def list_groups():
+        """View to list all public groups known by this instance
+        """
+
+        from calsocial.models import db, Group, GroupMembership, GroupVisibility
+
+        groups = Group.query
+
+        if current_user.is_authenticated:
+            groups = groups.outerjoin(GroupMembership) \
+                           .filter(db.or_(Group.visibility == GroupVisibility.public,
+                                          GroupMembership.profile == current_user.profile))
+        else:
+            groups = groups.filter(Group.visibility == GroupVisibility.public)
+
+        return render_template('group/list.html', groups=groups)
+
+    @staticmethod
+    @login_required
+    @RoutedMixin.route('/create', methods=['GET', 'POST'])
+    def create():
+        from datetime import datetime
+
+        from .forms import GroupForm
+        from .models import db, Group, GroupMemberLevel, GroupMembership
+
+        form = GroupForm()
+
+        if form.validate_on_submit():
+            group = Group(created_by=current_user.profile)
+            form.populate_obj(group)
+            db.session.add(group)
+
+            member = GroupMembership(group=group,
+                                     profile=current_user.profile,
+                                     level=GroupMemberLevel.admin,
+                                     accepted_at=datetime.utcnow(),
+                                     accepted_by=current_user.profile)
+            db.session.add(member)
+
+            db.session.commit()
+
+            return redirect(url_for('group.list'))
+
+        return render_template('group/create.html', form=form)
+
+    @staticmethod
+    @RoutedMixin.route('/<fqn>')
+    def display(fqn):
+        from .models import Group
+
+        group = Group.get_by_fqn(fqn)
+
+        if not group.visible_to(current_user.profile):
+            abort(404)
+
+        return render_template('group/display.html', group=group)
diff --git a/calsocial/models.py b/calsocial/models.py
index 7442b08..b42ebc4 100644
--- a/calsocial/models.py
+++ b/calsocial/models.py
@@ -123,6 +123,64 @@ EVENT_VISIBILITY_TRANSLATIONS = {
 }
 
 
+class GroupVisibility(Enum):
+    """Enumeration for group visibility
+    """
+
+    #: The group is secret, ie. completely unlisted
+    secret = 0
+
+    #: The group is closed, ie. it can be joined only with an invitation, but otherwise public
+    closed = 1
+
+    #: The group is public
+    public = 2
+
+    def __hash__(self):
+        return Enum.__hash__(self)
+
+    def __eq__(self, other):
+        if isinstance(other, str):
+            return self.name.lower() == other.lower()  # pylint: disable=no-member
+
+        if isinstance(other, (int, float)):
+            return self.value == other  # pylint: disable=comparison-with-callable
+
+        return Enum.__eq__(self, other)
+
+
+GROUP_VISIBILITY_TRANSLATIONS = {
+    GroupVisibility.secret: _('Secret'),
+    GroupVisibility.closed: _('Closed'),
+    GroupVisibility.public: _('Public'),
+}
+
+
+class GroupMemberLevel(Enum):
+    """Enumeration for group membership level
+    """
+
+    #: The member is a spectator only (ie. read only)
+    spectator = 0
+
+    #: The member is a user with all privileges
+    user = 1
+
+    #: The member is a moderator
+    moderator = 2
+
+    #: The member is an administrator
+    admin = 3
+
+
+GROUP_MEMBER_LEVEL_TRANSLATIONS = {
+    GroupMemberLevel.spectator: _('Spectator'),
+    GroupMemberLevel.user: _('User'),
+    GroupMemberLevel.moderator: _('Moderator'),
+    GroupMemberLevel.admin: _('Administrator'),
+}
+
+
 class SettingsProxy:
     """Proxy object to get settings for a user
     """
@@ -851,3 +909,150 @@ class AppState(app_state_base(db.Model)):  # pylint: disable=too-few-public-meth
 
     def __repr__(self):
         return f'<AppState {self.env}:{self.key}="{self.value}"'
+
+
+class Group(db.Model):
+    """Database model for groups
+    """
+
+    __tablename__ = 'groups'
+    __table_args__ = (
+        db.UniqueConstraint('handle', 'domain'),
+    )
+
+    id = db.Column(db.Integer(), primary_key=True)
+
+    handle = db.Column(db.String(length=50), nullable=False)
+
+    domain = db.Column(db.String(length=100), nullable=True)
+
+    display_name = db.Column(db.Unicode(length=100), nullable=True)
+
+    created_at = db.Column(db.DateTime(), default=datetime.utcnow)
+
+    created_by_id = db.Column(db.Integer(), db.ForeignKey('profiles.id'), nullable=False)
+
+    created_by = db.relationship('Profile')
+
+    default_level = db.Column(db.Enum(GroupMemberLevel))
+
+    visibility = db.Column(db.Enum(GroupVisibility), nullable=False)
+
+    @property
+    def members(self):
+        return Profile.query.join(GroupMembership, GroupMembership.profile_id == Profile.id).filter(GroupMembership.group == self)
+
+    @property
+    def fqn(self):
+        """The fully qualified name of the group
+
+        For local profiles, this is in the form ``!username``; for remote users, it’s in the form
+        ``!handle@domain``.
+        """
+
+        if not self.domain:
+            return f'!{self.handle}'
+
+        return f'!{self.handle}@{self.domain}'
+
+    @property
+    def url(self):
+        """Get the URL for this group
+        """
+
+        from flask import url_for
+
+        return url_for('group.display', fqn=self.fqn)
+
+    def __repr__(self):
+        return f'<Group {self.id}: !{self.handle}@{self.domain}>'
+
+    def __str__(self):
+        return self.fqn
+
+    @classmethod
+    def get_by_fqn(cls, fqn):
+        import re
+
+        match = re.match(r'^!([a-z0-9_]+)(@.*)?', fqn)
+
+        if not match:
+            raise ValueError(f'Invalid Group FQN {fqn}')
+
+        handle, domain = match.groups()
+
+        return Group.query.filter(Group.handle == handle).filter(Group.domain == domain).one()
+
+    def visible_to(self, profile):
+        """Checks whether this group is visible to ``profile``
+
+        It is so if the group is public or closed or, given it is secret, ``profile`` is a member
+        of the group.
+
+        :param profile: a :class:`Profile` object, or ``None`` to check for anonymous access
+        :type profile: Profile
+        :returns: ``True`` if the group is visible, ``False`` otherwise
+        :rtype: bool
+        """
+
+        if self.visibility == GroupVisibility.secret:
+            try:
+                GroupMembership.query \
+                               .filter(GroupMembership.group == self) \
+                               .filter(GroupMembership.profile == profile) \
+                               .one()
+            except NoResultFound:
+                return False
+
+        return True
+
+    def details_visible_to(self, profile):
+        """Checks whether the details of this group is visible to ``profile``
+
+        Details include member list and events shared with this group.
+
+        It is so if the group is public or ``profile`` is a member of the group.
+
+        :param profile: a :class:`Profile` object, or ``None`` to check for anonymous access
+        :type profile: Profile
+        :returns: ``True`` if the group is visible, ``False`` otherwise
+        :rtype: bool
+        """
+
+        if self.visibility != GroupVisibility.public:
+            try:
+                GroupMembership.query \
+                               .filter(GroupMembership.group == self) \
+                               .filter(GroupMembership.profile == profile) \
+                               .one()
+            except NoResultFound:
+                return False
+
+        return True
+
+
+class GroupMembership(db.Model):
+    """Database model for group membership
+    """
+
+    __tablename__ = 'group_members'
+
+    group_id = db.Column(db.Integer(), db.ForeignKey('groups.id'), primary_key=True)
+
+    group = db.relationship('Group')
+
+    profile_id = db.Column(db.Integer(), db.ForeignKey('profiles.id'), primary_key=True)
+
+    profile = db.relationship('Profile', foreign_keys=[profile_id])
+
+    level = db.Column(db.Enum(GroupMemberLevel), nullable=False)
+
+    requested_at = db.Column(db.DateTime(), default=datetime.utcnow, nullable=False)
+
+    joined_at = db.Column(db.DateTime(), nullable=True)
+
+    accepted_at = db.Column(db.DateTime(), nullable=True)
+
+    accepted_by_id = db.Column(db.Integer(), db.ForeignKey('profiles.id'), nullable=True)
+
+    accepted_by = db.relationship('Profile', foreign_keys=[accepted_by_id])
diff --git a/calsocial/templates/base.html b/calsocial/templates/base.html
index bd21da2..c0a1d57 100644
--- a/calsocial/templates/base.html
+++ b/calsocial/templates/base.html
@@ -34,6 +34,7 @@
     {%- endtrans %}
                     </div>
                     <a class="item" href="{{ url_for('hello') }}">{% trans %}Calendar view{% endtrans %}</a>
+                    <a class="item" href="{{ url_for('group.list_groups') }}">{% trans %}Groups{% endtrans %}</a>
                     <a class="item" href="{{ url_for('account.notifications') }}">{% trans %}Notifications{% endtrans %}</a>
                     <a class="item" href="{{ url_for('account.settings') }}">{% trans %}Settings{% endtrans %}</a>
                     <a class="item" href="{{ url_for('security.logout') }}">{% trans %}Logout{% endtrans %}</a>
diff --git a/calsocial/templates/group/create.html b/calsocial/templates/group/create.html
new file mode 100644
index 0000000..86c38a4
--- /dev/null
+++ b/calsocial/templates/group/create.html
@@ -0,0 +1,17 @@
+{% extends 'base.html' %}
+{% from '_macros.html' import field %}
+
+{% block content %}
+<h2>{% trans %}Create a group{% endtrans %}</h2>
+
+<form method="post" class="ui form">
+    {{ form.hidden_tag() }}
+
+    {{ field(form.handle) }}
+    {{ field(form.display_name) }}
+    {{ field(form.visibility) }}
+
+    <button class="ui primary button">{% trans %}Create{% endtrans %}</button>
+    <a href="{{ url_for('group.list_groups') }}" class="ui button">{% trans %}Cancel{% endtrans %}</a>
+</form>
+{% endblock content %}
diff --git a/calsocial/templates/group/display.html b/calsocial/templates/group/display.html
new file mode 100644
index 0000000..aa1cf1d
--- /dev/null
+++ b/calsocial/templates/group/display.html
@@ -0,0 +1,33 @@
+{% extends 'base.html' %}
+{% from '_macros.html' import profile_link %}
+
+{% block content %}
+<h2 class="ui header">
+    {% if group.visibility == 'secret' %}
+    [secret]
+    {% elif group.visibility == 'closed' %}
+    [closed]
+    {% elif group.visibility == 'public' %}
+    [public]
+    {% endif %}
+    {{group.display_name }}
+    <small>{{ group.fqn }}</small>
+</h2>
+    {% if not current_user.profile or not current_user.profile.is_member_of(group) %}
+        {% if group.visibility == 'public' %}
+Join
+        {% else %}
+Request membership
+        {% endif %}
+    {% else %}
+Invitation form
+    {% endif %}<br>
+    {% if group.details_visible_to(current_user.profile) %}
+<h2>{% trans %}Members{% endtrans %}</h2>
+        {% for member in group.members %}
+{{ profile_link(member) }}
+        {% endfor %}
+    {% else %}
+The details of this grop are not visible to you.
+    {% endif %}
+{% endblock content %}
diff --git a/calsocial/templates/group/list.html b/calsocial/templates/group/list.html
new file mode 100644
index 0000000..caf81b2
--- /dev/null
+++ b/calsocial/templates/group/list.html
@@ -0,0 +1,11 @@
+{% extends 'base.html' %}
+
+{% block content %}
+<h2>{% trans %}Groups{% endtrans %}</h2>
+{% for group in groups %}
+<a href="{{ group.url }}">{{ group }}</a>
+{% else %}
+{% trans %}No groups.{% endtrans %}
+<a href="{{ url_for('group.create') }}">{% trans %}Do you want to create one?{% endtrans %}
+{% endfor %}
+{% endblock content %}