The International Physicians for the Prevention of Nuclear War (IPPNW) is a contemporary example of a successful transnational non-governmental organization (NGO) which is providing leadership in accordance with Robert O. Keohane's definitional criteria. It has focused on the political issue-area of the prevention of nuclear war. Presently, it is cautiously expanding its mandate in order to engender international trust and co-operation in its role as an effective world leader. International or transnational NGOs have their roots in Quakerism of nearly 200 years ago. They take on a variety of forms but tend to share a distinguishing set of common characteristics. Since 1945, the number of international NGOs has grown impressively. The US affiliate of IPPNW, Physicians for Social Responsibility (PSR), anticipated the non-governmental function of IPPNW by almost two decades, essentially serving as a prototype in limited ways. PSR was founded in 1961 by a group of young doctors deeply concerned about the medical effects of nuclear war. From this founding group of US physicians came the leadership for IPPNW's formation in late 1980. The past successes and ongoing efforts of IPPNW as outlined in this paper demonstrate that IPPNW is serving in the needed role of a transnational organization acting as a midwife for the birthing of a new global comprehensive security system.