Abstract : The period since the end of the Cold War has witnessed a dramatic growth in the number of multilateral military operations, most loosely linked with the generic term 'peacekeeping.' The overwhelming majority of these operations have taken place under the auspices of the United Nations. They are a reflection of the rebirth of tribal nationalism, spreading religious xenophobia, and the threatened impoverishment and disintegration of Third World nation- states that have slipped their colonial moorings since World War II. As a result, we are witnessing new challenges to the United States, to the regional organizations in which we share membership, and to the United Nations system. This study effort will concentrate on the changing nature of peace operations, their likely impact on the U.S. military, and ways to improve and enhance the capabilities of various organizations to successfully complete future peace operations. The terms of reference will include the changing international security environment, the strengths and weaknesses of the United Nations and NATO in coping with existing security issues, and possible remedial actions. Policy proposals and recommendations include: a need to develop military doctrine that provides operational guidance for the broad range of activities that fall under the term 'peace operations', the urgent requirement for development of various types of unified command and control arrangements to meet future contingency operations; and the desirability of including civilian components in early stages of operational planning.