This handbook is intended to provide a comprehensive overview of the theories, methods and approaches for reducing HIV-associated risk behaviours. The handbook addresses the subject of HIV prevention from two interrelated perspectives. First, it presents the seminal theories currently used to guide the development and implementation of HIV prevention interventions. Second, it describes prevention approaches for diverse populations at risk of HIV infection. This handbook provides a compilation of knowledge on HIV prevention by the leading authorities in the field, and should be an important resource for students, researchers and clinicians in the field.