The development of large software systems is teamwork that requires tool support for coordinating cooperative activities, maintaining project control and sharing information. Existing collaborative environments that aim to support cooperative software development often try to predefine and automate the development process. This leads to problems since software development is a highly dynamic process where creativity, uncertainty, informal communication and incremental modification play important roles. We present an environment for distributed cooperative software development that supports informal communication as well as planning, defining, manipulating and supervising cooperative development activities. Our environment accommodates the highly dynamic development process primarily by providing guidelines for various activities and work processes that can be changed according to a clearly defined cooperation model.