diff --git a/app/models/message.rb b/app/models/message.rb
index 9ebc262d6..5f95f30d9 100644
--- a/app/models/message.rb
+++ b/app/models/message.rb
@@ -25,6 +25,8 @@ class Message < ActiveRecord::Base
     self
   end
 
+  validate :participant_of_parent_conversation
+
   def diaspora_handle
     self.author.diaspora_handle
   end
@@ -54,4 +56,13 @@ class Message < ActiveRecord::Base
   def parent= parent
     self.conversation = parent
   end
+
+  private
+  def participant_of_parent_conversation
+    if self.parent && !self.parent.participants.include?(self.author)
+      errors[:base] << "Author is not participating in the conversation"
+    else
+      true
+    end
+  end
 end
diff --git a/config/routes.rb b/config/routes.rb
index 6d8298244..1be26b55b 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -26,7 +26,9 @@ Diaspora::Application.routes.draw do
   resources :contacts
   resources :aspect_memberships, :only => [:destroy, :create]
 
+
   resources :conversations do
+    resources :messages, :only => [:create, :show]
     resource :conversation_visibility, :only => [:destroy], :path => '/visibility/'
   end
 
diff --git a/spec/models/message_spec.rb b/spec/models/message_spec.rb
index 7c09921fb..faf2bda98 100644
--- a/spec/models/message_spec.rb
+++ b/spec/models/message_spec.rb
@@ -18,6 +18,11 @@ describe Message do
     @xml = @message.to_diaspora_xml
   end
 
+  it 'validates that the author is a participant in the conversation' do
+    msg = Message.new(:text => 'yo', :author => eve.person, :conversation_id => @cnv.id)
+    pp msg.valid?
+  end
+
   describe '#before_create' do
     it 'signs the message' do
       @message.author_signature.should_not be_blank