diff --git a/server/lib/twenty/server/migration/4_add_milestones.rb b/server/lib/twenty/server/migration/4_add_milestones.rb
new file mode 100644
index 0000000..0d469ba
--- /dev/null
+++ b/server/lib/twenty/server/migration/4_add_milestones.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+Sequel.migration do
+  up do
+    create_table(:milestones) do
+      primary_key :id
+      String :name, null: false
+      Date :due_date, null: true
+      DateTime :created_at, null: false
+      DateTime :updated_at, null: false
+    end
+  end
+
+  down do
+    drop_table :milestones
+  end
+end
diff --git a/server/lib/twenty/server/migration/5_add_tasks_milestones.rb b/server/lib/twenty/server/migration/5_add_tasks_milestones.rb
new file mode 100644
index 0000000..8454bdc
--- /dev/null
+++ b/server/lib/twenty/server/migration/5_add_tasks_milestones.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+Sequel.migration do
+  up do
+    create_table(:tasks_milestones) do
+      primary_key :id
+      Integer :task_id, null: false
+      Integer :milestone_id, null: false
+      DateTime :created_at, null: false
+      DateTime :updated_at, null: false
+    end
+  end
+
+  down do
+    drop_table :tasks_milestones
+  end
+end
diff --git a/server/lib/twenty/server/model.rb b/server/lib/twenty/server/model.rb
index 2b20431..b6415ce 100644
--- a/server/lib/twenty/server/model.rb
+++ b/server/lib/twenty/server/model.rb
@@ -8,4 +8,5 @@ module Twenty::Model
 
   require_relative "model/project"
   require_relative "model/task"
+  require_relative "model/milestone"
 end
diff --git a/server/lib/twenty/server/model/milestone.rb b/server/lib/twenty/server/model/milestone.rb
new file mode 100644
index 0000000..a5c45e8
--- /dev/null
+++ b/server/lib/twenty/server/model/milestone.rb
@@ -0,0 +1,10 @@
+module Twenty
+  class Milestone < Sequel::Model
+    include Model
+    validates_presence_of :name
+
+    many_to_many :tasks,
+                 class_name: "Twenty::Task",
+                 join_table: :tasks_milestones
+  end
+end
diff --git a/server/lib/twenty/server/model/task.rb b/server/lib/twenty/server/model/task.rb
index e8748b8..15667fc 100644
--- a/server/lib/twenty/server/model/task.rb
+++ b/server/lib/twenty/server/model/task.rb
@@ -20,7 +20,11 @@ class Twenty::Task < Sequel::Model
   validates_presence_of :content
   validates_presence_of :project
   validates_inclusion_of :status, in: [STATUS_KEYS, *STATUS_KEYS.map(&:to_s)]
+
   many_to_one :project, class_name: "Twenty::Project"
+  many_to_many :milestones,
+               class_name: "Twenty::Milestone",
+               join_table: :tasks_milestones
 
   def status=(v)
     super(v.to_sym)