The UN Commission on Sustainable Development (CSD) was established in 1993 in order to follow up the commitments made by member states at the UN Conference on Environment and Development in Rio de Janeiro. As the CSD has recieved increasing criticism for its lack of effectiveness, a main objective for this study will be to evaluate what the Commission has accomplished during its first ten-year period. Furthermore, this report aims to describe and explain the mechanisms that affect the work of the CSD, in order to understand how it would be possible to enhance the potential for effectiveness. The first part of the analysis concentrates on evaluating and determining the degree of the CSD’s accomplishments by comparing them to the CSD’s mandate. Based on the perspectives of ‘distribution of capabilities’, ‘institutional design’ and ‘entrepreneurial leadership’, I evaluate which mechanisms explain the degree of the CSD’s performances in the second part. I conclude that the CSD has achieved some results in monitoring the process and promoting dialogue, due to the role of the secretariat and nonstate actors. However, the member states’ positions and interests have had a major impact on the low degree of accomplishments in the area of policy guidance.