The spread of Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) depends very much on the way people behave. Individuals from some groups have been successfully persuaded to modify behaviors that put them at increased risk of HIV infection. The salient questions for future AIDS prevention and control programs are about how this modification actually came about, and how the progress achieved can be consolidated. Psychosocial factors have a vital role in influencing the behavior of both individuals and groups. At the fourth in a series of World Health Organization meetings on AIDS issues, 76 participants met to discuss the psychosocial aspects of HIV infection and AIDS, and to look at the importance of behavioral factors in planning and evaluating strategies for prevention and control. They felt that studies of knowledge, attitudes, and behaviors and practices can be a valuable tool for national AIDS programs if carried out and used appropriately. They emphasized the importance of maintaining the quality of program monitoring and evaluation. They identified school and college students as vital target audiences for AIDS education, and providers of health, education, and social services for training in AIDS issues. Finally, they encouraged policy-makers and program managers to establish partnerships with journalists, as the most efficient means of reaching the largest number of people. (LLL)