The integration of psychological, social, and biological components of human sexuality in this text is facilitated by the authors' combined academic and professional backgrounds. Robert Crooks has a Ph.D. in psychology. His graduate training stressed clinical and physiological psychology, and he has considerable background in sociology. His involvement with teaching human sexuality classes at the university, college, and medical school levels spans over two decades. Bob and his wife, Sami Tucker, have been involved in the establishment and implementation of HIV/AIDS intervention programs in two areas of Kenya, one in the central region and one in a coastal area. Over the previous 12 years their work with these projects includes designing a research strategy for assessing behavior change, developing a peer educator-based educational strategy, and conducting training sessions for Kenyan peer educator staff. Over many years they have traveled to African frequently and devoted many months to the evolving Kenyan programs.