diff --git a/app/models/context.rb b/app/models/context.rb
index d5e5be00..dd78f9bc 100644
--- a/app/models/context.rb
+++ b/app/models/context.rb
@@ -5,11 +5,32 @@ class Context < ActiveRecord::Base
   has_many :recurring_todos, :dependent => :delete_all
   belongs_to :user
 
-  scope :active, :conditions => { :hide => false }
-  scope :hidden, :conditions => { :hide => true }
+  scope :active, :conditions => { :state => :active }
+  scope :hidden, :conditions => { :state => :hide }
 
   acts_as_list :scope => :user, :top_of_list => 0
 
+  # state machine
+  include AASM
+  aasm_column :state
+  aasm_initial_state :active
+
+  aasm_state :active
+  aasm_state :closed
+  aasm_state :hidden
+
+  aasm_event :close do
+    transitions :to => :closed, :from => [:active, :hidden], :guard => :no_active_todos?
+  end
+
+  aasm_event :hide do
+    transitions :to => :hidden, :from => [:active, :closed]
+  end
+
+  aasm_event :activate do
+    transitions :to => :active, :from => [:closed, :hidden]
+  end
+
   attr_protected :user
 
   validates_presence_of :name, :message => "context must have a name"
@@ -20,10 +41,6 @@ class Context < ActiveRecord::Base
     NullContext.new
   end
 
-  def hidden?
-    self.hide == true || self.hide == 1
-  end
-
   def title
     name
   end
@@ -32,6 +49,10 @@ class Context < ActiveRecord::Base
     @new_record_before_save
   end
 
+  def no_active_todos?
+    return todos.active.count == 0
+  end
+
 end
 
 class NullContext
diff --git a/db/migrate/20130227205845_add_state_to_context.rb b/db/migrate/20130227205845_add_state_to_context.rb
new file mode 100644
index 00000000..8e0d59ff
--- /dev/null
+++ b/db/migrate/20130227205845_add_state_to_context.rb
@@ -0,0 +1,22 @@
+class AddStateToContext < ActiveRecord::Migration
+
+  class Context < ActiveRecord::Base
+  end
+
+  def up
+    add_column :contexts, :state, :string, :limit => 20, :null => false
+    Context.reset_column_information
+    Context.all.each do |c|
+		c.state = c.hide ? 'hidden' : 'active'
+		c.save!
+    end
+    remove_column :contexts, :hide
+  end
+
+  def down
+  	add_column :contexts, :hide, :boolean, :default => false
+    Context.reset_column_information
+  	Context.all.each { |c| c.hide = ( c.state == 'hidden' ) }
+  	remove_column :contexts, :state
+  end
+end
diff --git a/test/fixtures/contexts.yml b/test/fixtures/contexts.yml
index 49ce9d2f..15bfd1d3 100644
--- a/test/fixtures/contexts.yml
+++ b/test/fixtures/contexts.yml
@@ -10,7 +10,7 @@ agenda:
   id: 1
   name: agenda
   position: 1
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -19,7 +19,7 @@ call:
   id: 2
   name: call
   position: 2
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -28,7 +28,7 @@ email:
   id: 3
   name: email
   position: 3
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -37,7 +37,7 @@ errand:
   id: 4
   name: errand
   position: 4
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -46,7 +46,7 @@ lab:
   id: 5
   name: lab
   position: 5
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -55,7 +55,7 @@ library:
   id: 6
   name: library
   position: 6
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -64,7 +64,7 @@ freetime:
   id: 7
   name: freetime
   position: 7
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -73,7 +73,7 @@ office:
   id: 8
   name: office
   position: 8
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -82,7 +82,7 @@ waitingfor:
   id: 9
   name: waiting for
   position: 9
-  hide: false
+  state: active
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -91,7 +91,7 @@ office_otheruser:
   id: 10
   name: office
   position: 1
-  hide: false
+  state: active
   user_id: 2
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -100,7 +100,7 @@ waitingfor_otheruser:
   id: 11
   name: waiting for
   position: 2
-  hide: false
+  state: active
   user_id: 2
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -109,7 +109,7 @@ someday_maybe:
   id: 12
   name: someday maybe
   position: 10
-  hide: true
+  state: hidden
   user_id: 1
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -118,7 +118,7 @@ inbox:
   id: 13
   name: Inbox
   position: 1
-  hide: false
+  state: active
   user_id: 4
   created_at: <%= today %>
   updated_at: <%= today %>
@@ -127,7 +127,7 @@ anothercontext:
   id: 14
   name: anothercontext
   position: 2
-  hide: false
+  state: active
   user_id: 4
   created_at: <%= today %>
   updated_at: <%= today %>
diff --git a/test/unit/context_test.rb b/test/unit/context_test.rb
index da7e14fe..b3b56196 100644
--- a/test/unit/context_test.rb
+++ b/test/unit/context_test.rb
@@ -54,14 +54,6 @@ class ContextTest < ActiveSupport::TestCase
     assert_equal @agenda.name, @agenda.title
   end
 
-  def test_hidden_attr_reader
-    assert !@agenda.hidden?
-    @agenda.hide = true
-    @agenda.save!
-    @agenda.reload
-    assert_equal true, @agenda.hidden?
-  end
-
   def test_null_object
     c = Context.null_object
     assert c.nil?
@@ -75,4 +67,34 @@ class ContextTest < ActiveSupport::TestCase
     assert c.new_record_before_save?, "newly created record should be new_record"
   end
 
+  def test_hide_context
+    assert @agenda.active?
+    @agenda.hide!
+    assert @agenda.hidden?
+  end
+
+  def test_closing_context_guarded_for_active_todos
+    assert @agenda.active?
+    assert AASM::InvalidTransition do
+      @agenda.close!
+    end
+
+    @agenda.todos.active.each {|t| t.complete! }
+    @agenda.close!
+    assert @agenda.closed?
+  end
+
+  def test_activating_closed_context
+    # given a context @agenda that is closed
+    @agenda.todos.active.each {|t| t.complete! }
+    @agenda.close!
+    assert @agenda.closed?
+
+    # when I activate @agenda
+    @agenda.activate!
+
+    # then @agenda should have an active state
+    assert @agenda.active?
+  end
+
 end