HIV/STD prevention programs are increasingly guided by behavioral rather than by disease indicators. Relevant HIV/STD-related behavioral information is currently available from a variety of surveys and surveillance systems at three levels: general population, infected populations, and high-risk populations. However, the utility of these systems for local program development is limited due to lack of standardization. In 1997 a Centers for Disease Control and Prevention working group was formed to develop a core set of items for HIV/STD behavioral surveillance for use across surveys. Core items were chosen on the basis of existing surveys and surveillance systems, relevant literature, testing in a cognitive laboratory, and field pilot-testing. A draft of the core set of sexual behavior questions is available on the web at http://www.cdc.gov/nchstp/od/core-workgroup for review and feedback. Questions on drug use, including drug injection practices, as well as questions on HIV testing and sexually transmitted diseases are in preparation and will also be posted on the web site for review.