In distance education programs with a large number of students, the organization and facilitation of collaborative writing projects are particularly challenging. Teachers must specify the didactical design and group formation, supervise and support distributed groups, grade, and finally evaluate the learning experiences. Distributed student groups need their own workspace including both, support for a structured writing process including necessary instructions and materials as well as tools for collaborative text editing, communication, coordination, and providing formative and summative feedback. Current approaches to support collaborative writing in education are mostly based on the use of Web 2.0 applications, such as Wikis and Weblogs, or Collaborative real-time text editors, failing to support teachers and students appropriately. As a consequence, teachers often refrain from implementing collaborative writing projects in large scale distance learning courses. We introduce a process model of a collaborative writing project aimed at creating a summary of a research paper and present the architecture and implementation of a Collaborative Learning Platform implementing Collaborative Writing Activities by an extension of a Learning Management System and integrating it with a collaboration environment. The platform supports the phases and activities of the process model and provides distributed teachers and students with integrated support throughout the collaborative writing project lifecycle. Our experience shows that the platform provides a scalable, responsive, and robust environment for collaborative writing and is accepted by teachers and students. It provides the basis for the analysis of collaborative writing behavior and further research.