The American Psychological Association (APA), which provides the secretariat for the Global Psychology Alliance (GPA), has been accredited by the United Nations (UN) Economic and Social Council (ECOSOC) and Department of Global Communications (DGC) since 1999. APA has teams of Representatives in New York and Geneva - the latter in collaboration with the European Federation of Psychologists' Associations and the Federation of Swiss Psychologists - who bring psychological science to bear on the work of the UN through educating and advocating to foster dialogue and collaboration between psychologists, UN staff, member state representatives, and other NGOs to encourage the development of psychologically informed policies, practices, and programs. GPA provides one of psychology's most powerful tools at the UN through the global expertise represented in its membership. This talk will explain how Representatives at the UN collaborate with GPA members to advance concrete outcomes at the UN, for example, passage of a seminal General Assembly Resolution on Mental Health and Psychosocial Support in which the countries of the world pledged to prioritize mental health in national policymaking.