A concern with international cooperation in psychology has been present since the beginnings of psychology as a science. In this article, the author traces the development of international cooperation from the late 19th century to the present day to document the interesting ways in which the forms of collaboration have always been related to the large social and political contexts of which they are a part. This historical material is followed by an autobiographical account of the author's own involvement in cooperative international research to illustrate how such activity can play out. A few selected collaborative enterprises are then described to emphasize the point that psychology stands to benefit enormously from continued international cooperation, especially in times of international conflict such as that being experienced at the present time. ((c) 2006 APA, all rights reserved).