We initiated a study of high-risk heterosexual females and their male partners. The goal was to characterize the partnerships, quantify the prevalence of high-risk male behaviors and characteristics, and to assess whether females in these partnerships would be able to accurately and consistently describe their partners' risk conditions. Seventy-four percent (73.6%) of partnerships reported frequent unprotected sex (condom use during fewer than half their sexual encounters) and 55.9% reported frequent drug or alcohol use during sex (drug or alcohol use during more than half their sexual encounters). Two-thirds (66.7%) of men reported concurrent sexual partnerships and 40.8% reported a history of STDs. The women's assessments of their partners' behaviors often differed from the behaviors and characteristics reported by the women's male partners.