User blog comment:Lancer1289/BioWare gets on the Multiplayer bandwagon/@comment-25305799-20111012191341/@comment-4355416-20111012194340

Your friends actually wont be able to play with you during the campaign because co-op doesnt take place in the regular story campaign the way it does in Halo or Gears of War. Co-op will have everyone on the team playing as completely new (customizable) characters in horde-style battles. The story-based campaign is still singleplayer only.