The Multilateral Organization Performance Assessment Network (MOPAN) aims to strengthen multilateral organizations’ contributions to overall greater development and humanitarian results. MOPAN is a network of 17 donors (Australia, Canada, Denmark, Finland, France, Germany, Ireland, Japan, Luxembourg, the Netherlands, Norway, Republic of Korea, Spain, Sweden, Switzerland, the United Kingdom, and the United States) with a common interest in assessing the organizational and development effectiveness of the major multilateral organizations they fund. The MOPAN methodology launched in 2015, examines multilateral organizations across five areas: strategic, operational, relationship and performance management, as well as development effectiveness. MOPAN’s findings: (1) generate relevant and credible information that MOPAN members can use to meet their accountability requirements; (2) support dialogue between donors, multilateral organizations and their partners at the country level on how to improve effectiveness and learning; and (3) respond to the recognized need for a common, comprehensive multilateral organization assessment system.