From a software engineering perspective the World Wide Web is a new application platform. The implementation model that the Web is based on makes it difficult to apply classic process models to the development and even more the evolution of Web-applications. Component-based software development seems to be a promising approach for addressing key requirements of the very dynamic field of Webapplication development and evolution. But such an approach requires dedicated support. The WebComposition Process Model addresses this requirement by describing the component-based development of Web-applications. It uses an XML-based markup language to seamlessly integrate with existing Webstandards. For the coordination of components the concept of an open process model with an explicit support for reuse is introduced. By describing application domains using domain-components the process model addresses the need for a controlled evolution of Web applications.