In this paper we define the concept of conversation policies: declarative specifications that govern communications between software agents using an agent communication language. We discuss the role that conversation policies play in agent communication, and suggest several subtypes of conversation policy. Our reasoning suggests, contrary to current transition net approaches to specifying conversation policies that conversation policies are best modeled as sets of fine-grained constraints on ACL usage. These constraints then define the computational process models that are implemented in agents. The Roots of Conversation Policies The dream of agent interoperability is commonly thought to rest on three main characteristics shared by the interoperating agents: