If the number of users within a workflow management system (WFMS) increases, a central workflow server (WF– server) and a single local area network (LAN) may become overloaded. The approach presented in this paper describes an execution environment which is able to manage a growing number of users by adding new servers and subnets. The basic idea is to decompose processes into parts which are controlled by different WF–servers. That is, during the execution of a workflow instance its execution (step) control may migrate from one WF–server to another. By selecting the appropriate physical servers (for hosting the WF–servers) in the appropriate LANs, communication costs and individual WF–server workload can be reduced significantly.