This article explores the role of the United Nations in development in the context of both the current critiques of the UN and the failure of the 2005 New York summit to reach agreement on a program of reform. While the work of its specialist agencies presents the most visible face of the UN’s contribution to global development; the UN through its efforts to influence international debates on development policy, in particular as the convenor of international conferences, also plays a key intellectual leadership role in rethinking approaches to development. It is argued that in spite of the justifiable criticism of many aspects of the UN agencies, on balance the UN has played a positive role in promoting development and has been an alternative voice to the major international powers. Future reform should ensure that the UN can continue to make this contribution.