This book constitutes the refereed proceedings of the 6th International Conference on Cooperative Design, Visualization, and Engineering, CDVE 2009, held in Luxembourg, Luxembourg, in September 2009. The 58 revised full papers presented were carefully reviewed and selected from numerous submissions. The papers focus on two main aspects: 1. Cooperation in the software development process, addressing topics such as the development of shared mental models; tools for shared projects; sharing links for cross-media information spaces; and sharing resources and transfer of knowledge among team members. 2. The variety of cooperative software products, ranging from cooperative support for music creation; cooperative process management systems; cooperative visualization systems for geographic information; cooperative cultural information sharing platforms; cooperative reasoning systems; cooperative sensor networks for environment monitoring; to remote cooperative video vehicle monitoring systems.