The Agency for International Development (AID) participant training program was examined to determine its impact on developing countries. One hundred and thirty-four senior officials in Ghana and Thailand provided 492 reports on: (1) indicators of participant achievements; (2) impact-producing characteristics; and (3) contributions attributed to participant training. An evaluation kit, or methodology, was field tested in Korea, the Philippines, and Brazil. Three hundred and sixty-four local officials reported 2,871 critical incidents. The data clearly showed that AID participants trained in the U.S. made significant contributions to the development of their countries, and that 58% of these contributions could be linked to some specifiable aspect of the participant training. The author predicted that participants would continue to make beneficial contributions in areas such as agriculture, economic planning, health, and public administration. Follow-up studies that would provide useful policy guidance were suggested. (Author/GDC)