IOE is a member of the European Evaluation Society (EES) since 2013. The EES was created over seventeen years ago, with the mandate to stimulate, guide and promote the theory, practice and utilization of evaluation in Europe and beyond. EES  provides platforms for fulsome debate, for the dissemination of evaluation knowledge and for closer engagement with other disciplines.

IOE is the only evaluation office among the United Nations specialized agencies, programmes or funds to be a member of EES.