North American Invitational Model United Nations | 158 followers on LinkedIn. The North American Invitational Model United Nations (NAIMUN) is an annual high school Model UN conference planned and executed by the Georgetown International Relations Association, a 501(c)3 non-profit focused on increasing youth education in international affairs. Since its inception in 1963, NAIMUN is hosted each February in Washington, D.C. and welcomes over 3300+ high school students from around the world as conference participants. It is led by 300 Georgetown University staffers.