This book was written to provide public health leaders, community organizers, policymakers, community-based agency directors, and health educators with the most accurate information available on developing prevention strategies to reduce the spread of human immunodeficiency virus (HIV) in communities throughout the United States. In the late 1980s the San Francisco (California) Department of Health, together with a wide range of organizations, agencies, community groups, and individuals, developed a response to the epidemic that has served as a model both nationally and worldwide, and the lessons learned in San Francisco are presented in this book as a case study of a community in action. Part I of the book, Understanding the HIV Epidemic, provides the basic foundation for understanding the emergence and epidemiology of the epidemic. Part II, the San Francisco Response, presents three chapters detailing different aspects of the prevention effort in San Francisco. Part III, HIV Prevention in Your Community, provides nuts and bolts expertise concerning the development, design, and implementation of prevention programs. Individual chapters include: (1) "A Modern Epidemic Emerges: History and Context" (Renata Kiefer and Stephen Hulley); (2) "Patterns of the Epidemic and Public Health Implications" (Renata Kiefer, Joseph Guydish, Katherine Haynes, George Lemp and Stephen Hulley); (3) "AIDS: Putting the Models to the Test" (Margaret Chesney and Thomas Coates); (4) "A City Responds to Crisis: Creating New Approaches" (Jeffrey Amory); (5) "San Francisco's Prevention Partnership: Issues and Challenges" (Jeffrey Amory); (6) "Lessons from San Francisco: Principles of Program Design" (Ron Stall, Chuck Frutchey, Mindy Thompson Fullilove, and Pat Christen); (7) "Planning and Implementing Community Strategies" (Pat Franks, Henrik Blum, Thomas Coates, Edward Morales, and Paul Gibson); and (8) "Ending the HIV Epidemic: A Call for Community Action" (Timothy Wolfred). (NB)