We present a schema and process evolution tool, called the Evolver, for the MARVEL process-centered environment. The Evolver analyzes the differences between the new and installed process models of an existing environment, detecting each case where the notion of consistency defined by the process model has been strengthened or weakened. The Evolver then automatically updates the environment's objectbase to guarantee that the objects are consistent according to the new specifications. The Evolver can be applied while the installed process is in progre,,s, temporarily halting normal operation while it updates the objectbase, after which development continues using the new process. We have had several months of experience using the Evolver to make repeated changes in the process that supports our own further development of MARVEL, and include in this paper one small but practical example of a recent change made to a real MARVEL process.