Workflow Management Systems (WfMS) are expanding from Intranets to Extranets. The automation of inter-organization processes requires interaction between heterogeneous distributed systems, and coordination becomes an issue. While traditional solutions are based on strong centralization, we pursue a completely distributed approach. In this paper, we propose a process decomposition technique for workflow processes. Starting from a generic workflow definition, we derive role-specific projections of the processes involved. Each projection is an autonomous process that embeds the (explicit) behaviour the original process assigned a specific role, and the (implicit) coordination logic for inter-role interaction. Projections can be distributed for execution on distinct process engines, and the network of projections reproduces the semantics of the original workflow process. The enactment environment for the projections is a lightweight infrastructure we implemented using Java RMI.