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 Web-application 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 Web-standards. 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.