Social networks (SNs) enable physically distributed groups to communicate seamlessly. Unfortunately such communi- cation can be easily mined by adversaries in attempts to breach users’ privacy or suppress open discussion on sensi- tive topics. While anonymous posting can help protect users by hiding the link between individuals and the messages they post, existing anonymization schemes are centralized or vul- nerable to well-known attacks. To offer stronger protection for free speech online, we propose a method for anonymous group communication using SNs called Faceless. Faceless leverages existing Internet-based SNs for convenience in managing groups and users’ public identities, but augments these centralized services with a decentralized anonymous posting overlay offering provable anonymity guarantees, re- sisting even group infiltration and traffic analysis attacks.