IOE is a member of the Evaluation Cooperation Group (ECG) of the multilateral development banks since 2010. ECG was established by the heads of evaluation of multilateral development banks to promote evaluation harmonization among its members. ECG has developed and uses Good Practice Standards (GPS) and benchmarking studies to assess the extent to which the GPS are applied by its members.

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