The Women's Interagency HIV Study (WIHS) is a large, comprehensive prospective cohort study designed to investigate a spectrum of questions relating to the pathogenesis and natural history of HIV infection among women in the era of highly active antiretroviral therapy. The purpose of this application is to extend support of the WIHS Data Management and Analysis Center (WDMAC) that will continue to provide leadership in contributing epidemiological and statistical expertise to the WIHS research agenda, provide a stable and efficient data management system, and provide coordination of study protocols and WIHS investigator initiatives to enhance the quality and validity of the data and the scientific research in the WIHS. The specific aims of WDMAC are: (1) To provide scientific leadership in a Clinical Research Agenda focusing on analytical methods, strategies for improving antiretroviral therapy adherence using both modeling and an innovative randomized behavioral intervention trial, and in-depth cohort profiles of the clinical epidemiology of HIV; (2) To optimize the contributions of the WIHS to the understanding of the pathogenesis and natural and treated history of HIV infection in women through collaboration and scientific partnerships; (3) To coordinate research initiatives and scientific presentations by facilitating communication among WIHS and external investigators, Working Groups and committees; to orchestrate study protocol and form revision; and produce study-wide profiles of cohort characteristics (WIHS Dossier), and scientific publications (WIHS Archives); (4) To maintain and refine our web-based data management system and assess feasibility and coordinate the transition from paper-based data collection. We will continue our systems for: tracking the storage and transfer of biological specimens at national repositories, producing annual public data sets, and conducting training in methods that facilitates the appropriate use of study data for local research; (5) To continue our quality assurance program in partnership with the clinical sites that integrates expertise in data management, study coordination, statistical methodology, and scientific disciplines. This program will continue to monitor study-wide quality and promote adherence and training for standardized data collection.