diff --git a/app/models/group.rb b/app/models/group.rb
index 76042b3e3fd..e307624e965 100644
--- a/app/models/group.rb
+++ b/app/models/group.rb
@@ -23,6 +23,8 @@ class Group < Namespace
   has_many :group_members, dependent: :destroy, as: :source, class_name: 'GroupMember'
   alias_method :members, :group_members
   has_many :users, through: :group_members
+  has_many :project_group_links, dependent: :destroy
+  has_many :shared_projects, through: :project_group_links, source: :project
 
   validate :avatar_type, if: ->(user) { user.avatar.present? && user.avatar_changed? }
   validates :avatar, file_size: { maximum: 200.kilobytes.to_i }
diff --git a/app/models/project.rb b/app/models/project.rb
index 65829bec77a..2232637f1f1 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -151,6 +151,8 @@ class Project < ActiveRecord::Base
   has_many :releases, dependent: :destroy
   has_many :lfs_objects_projects, dependent: :destroy
   has_many :lfs_objects, through: :lfs_objects_projects
+  has_many :project_group_links, dependent: :destroy
+  has_many :invited_groups, through: :project_group_links, source: :group
   has_many :todos, dependent: :destroy
 
   has_one :import_data, dependent: :destroy, class_name: "ProjectImportData"
diff --git a/app/models/project_group_link.rb b/app/models/project_group_link.rb
new file mode 100644
index 00000000000..e52a6bd7c84
--- /dev/null
+++ b/app/models/project_group_link.rb
@@ -0,0 +1,36 @@
+class ProjectGroupLink < ActiveRecord::Base
+  GUEST     = 10
+  REPORTER  = 20
+  DEVELOPER = 30
+  MASTER    = 40
+
+  belongs_to :project
+  belongs_to :group
+
+  validates :project_id, presence: true
+  validates :group_id, presence: true
+  validates :group_id, uniqueness: { scope: [:project_id], message: "already shared with this group" }
+  validates :group_access, presence: true
+  validates :group_access, inclusion: { in: Gitlab::Access.values }, presence: true
+  validate :different_group
+
+  def self.access_options
+    Gitlab::Access.options
+  end
+
+  def self.default_access
+    DEVELOPER
+  end
+
+  def human_access
+    self.class.access_options.key(self.group_access)
+  end
+
+  private 
+
+  def different_group
+    if self.group && self.project && self.project.group == self.group
+      errors.add(:base, "Project cannot be shared with the project it is in.")
+    end
+  end
+end
diff --git a/db/migrate/20130711063759_create_project_group_links.rb b/db/migrate/20130711063759_create_project_group_links.rb
new file mode 100644
index 00000000000..395083f2a03
--- /dev/null
+++ b/db/migrate/20130711063759_create_project_group_links.rb
@@ -0,0 +1,10 @@
+class CreateProjectGroupLinks < ActiveRecord::Migration
+  def change
+    create_table :project_group_links do |t|
+      t.integer :project_id, null: false
+      t.integer :group_id, null: false
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20130820102832_add_access_to_project_group_link.rb b/db/migrate/20130820102832_add_access_to_project_group_link.rb
new file mode 100644
index 00000000000..00e3947a6bb
--- /dev/null
+++ b/db/migrate/20130820102832_add_access_to_project_group_link.rb
@@ -0,0 +1,5 @@
+class AddAccessToProjectGroupLink < ActiveRecord::Migration
+  def change
+    add_column :project_group_links, :group_access, :integer, null: false, default: ProjectGroupLink.default_access
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index a74b86d8e2f..89e8c9e67b0 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -656,6 +656,14 @@ ActiveRecord::Schema.define(version: 20160309140734) do
   add_index "oauth_applications", ["owner_id", "owner_type"], name: "index_oauth_applications_on_owner_id_and_owner_type", using: :btree
   add_index "oauth_applications", ["uid"], name: "index_oauth_applications_on_uid", unique: true, using: :btree
 
+  create_table "project_group_links", force: :cascade do |t|
+    t.integer  "project_id",                null: false
+    t.integer  "group_id",                  null: false
+    t.datetime "created_at"
+    t.datetime "updated_at"
+    t.integer  "group_access", default: 30, null: false
+  end
+
   create_table "project_import_data", force: :cascade do |t|
     t.integer "project_id"
     t.text    "data"
@@ -749,9 +757,9 @@ ActiveRecord::Schema.define(version: 20160309140734) do
     t.string   "type"
     t.string   "title"
     t.integer  "project_id"
-    t.datetime "created_at",                               null: false
-    t.datetime "updated_at",                               null: false
-    t.boolean  "active",                                   null: false
+    t.datetime "created_at"
+    t.datetime "updated_at"
+    t.boolean  "active",                default: false,    null: false
     t.text     "properties"
     t.boolean  "template",              default: false
     t.boolean  "push_events",           default: true
diff --git a/spec/factories/project_group_links.rb b/spec/factories/project_group_links.rb
new file mode 100644
index 00000000000..e73cc05f9d7
--- /dev/null
+++ b/spec/factories/project_group_links.rb
@@ -0,0 +1,6 @@
+FactoryGirl.define do
+  factory :project_group_link do
+    project
+    group
+  end
+end
diff --git a/spec/models/project_group_link_spec.rb b/spec/models/project_group_link_spec.rb
new file mode 100644
index 00000000000..2fa6715fcaf
--- /dev/null
+++ b/spec/models/project_group_link_spec.rb
@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+describe ProjectGroupLink do
+  describe "Associations" do
+    it { should belong_to(:group) }
+    it { should belong_to(:project) }
+  end
+
+  describe "Validation" do
+    let!(:project_group_link) { create(:project_group_link) }
+
+    it { should validate_presence_of(:project_id) }
+    it { should validate_uniqueness_of(:group_id).scoped_to(:project_id).with_message(/already shared/) }
+    it { should validate_presence_of(:group_id) }
+    it { should validate_presence_of(:group_access) }
+  end
+end