The Behavioral Risk Factor Surveillance System (BRFSS) is the world's largest, on-going telephone health survey system. As a result, surveys were developed and conducted to monitor state-level prevalence of the major behavioral risks among adults associated with premature morbidity and mortality. The basic philosophy was to collect data on actual behaviors, rather than on attitudes or knowledge, that would be especially useful for planning, initiating, supporting, and evaluating health promotion and disease prevention programs. Currently data are collected monthly in all 50 states.