The importance of agent communication for multi-agent systems is, of course, beyond any doubt. However, the importance of research in this area seems less obvious. After several years with lots of discussions about standard agent communication languages and possible semantics for them it seems people have the feeling that all the issues in this area are settled. Despite some criticism on FIPA ACL this seems to be the de facto standard for agent communication. Especially after the JADE platform (which is probably the widest used in academic circles) was made FIPA compliant. However, there is still a wide gap between being able to parse and generate messages that conform to the FIPA ACL standard and being able to perform meaningful conversations.Inordertoforceorevenjustsupportagentstoperformmeaningfulconversations some form of a shared semantics of the communication process is needed. Since it is impossible to verify compliance of agents based on internal structures of the agents (that cannot be inspected) the semantics should be based on concepts that are externally observable. Hence the growing interest in the use of social concepts that can be observed and verified outside the agents. In thecontextofthese developmentswe are happyto presentthis specialissue.The papers selected for this special issue on agent communication are based on presentations at the Agent Communication workshop of 2004, held in New York. They clearly indicate the general trend in the past few years towards the use of social concepts in defining the semantics of agent communication. Especially “social commitments” and deontic concepts such as “obligations” seem to become a central element in this respect. In three of the four papers in this special issue social commitments form the basis of the theory discussed in that paper. The fourth paper is based on the use of obligations and permissions. The paper of Fornara et. al. discusses the use of “institutions” as an abstract set of rules that describe how social commitments are changed based on communication