DESCRIPTION (Applicant's Abstract): The International Core aims to build partnerships between CAPS scientists and alumni of our Collaborative Research in Developing Countries Program, and promotes productive international research in partnership with our alumni. In previous grant cycles, CAPS has successfully developed a research and training program for scientists from the developing world and a broad portfolio and small-scale international research projects conducted by CAPS scientists in partnership with our program alumni. Together we have aimed to provide important contributions toward understanding how to prevent HIV transmission and how to care for the HIV-infected in the developing world. However, as we transition from a P50 to a P30 grant and there is necessarily less money available, we have reconfigured the International Core to facilitate collaborative international research and to capitalize on our network of 91 program alumni in 32 countries. While we have sought and will continue to seek funds from other sources to refine and continue the training portions of the International Core during the next 5-year grant period, our principal objective will be to facilitate high-quality international research by creating effective and productive partnerships of CAPS scientists and our alumni. We believe that the time is right to capitalize on our investment in international research mining and to utilize the resource capacity we have built in the developing world through our alumni network and institutional connections more fully and more systematically. Our research will be conducted in selected countries where we have established our strongest networks of alumni, will be thematically focused, and will allow us to continue and strengthen our collaborations with developing country scientists and institutions.