Workflow management systems (WfMSs) are accepted worldwide due to their capability to model and control business processes. With WfMS, enterprises can improve work efficiency and react to the emergent situation quickly. However, most WfMSs adopt the centralized architecture in an organization so that they usually lack of a cooperative communication mechanism across different organizations. In this paper, we propose a cooperative framework for inter-organizational workflow systems. The framework consists of an inter-workflow meta-model, CA-PLAN (Cooperative Agentflow Process LANguage), and a prototype system based on Agentflow, a system developed in our laboratory. The cooperation mechanism between WfMSs in CA-PLAN is modeled as a Remote Call Process (RCP) paradigm. A Process Service is a mechanism that defines a process to participate in an inter-organizational process among different WfMSs and specifies the associated arguments in and out. A Remote Process is a proxy mechanism that refers to a process service on another WfMS. RCP provides the mechanism by which the process service and the remote process communicate and pass information back and forth and process monitor mechanism. The mechanism, also allowing dynamic changes and reconfiguration, can adapt dynamic and competitive business environment. Through RCP, the cooperative process across organizations becomes simple, faster, and flexible.