The need for evaluations increases for several reasons. First, decision-makers are interested in the views of various stakeholders. Second, by striving for efficiency, the public sector increases the readiness for learning through feedback. Third, regulations and bans are increasingly replaced with voluntary agreements, subsidies, informational and consulting programs. Evaluations measure not only the effectiveness of a policy or a program, but they also favour systematic learning for all participants involved in the sustainable development processes. In our theoretical research projects we develop interdisciplinary methods of evaluation in the context of sustainable development. In applied projects we conduct evaluations of policies, projects and programmes for municipalities, counties and the federal government. By fostering an international research network, we want to increase the scholarly exchange on methodological issues as well as develop innovative projects.