Existing knowledge and beliefs related to HIV vaccines provide an important basis for the development of risk communication messages to support future HIV vaccine dissemination. This study explored HIV vaccine mental models among adults from segments of the population disproportionately affected by HIV/AIDS. Nine focus groups were conducted with participants (N = 99; median age = 33 years; 48% female; 22% African American, 44% Latino, and 28% white) recruited from needle exchange sites, public clinics, and gay community centers in Los Angeles. Data were analyzed using narrative thematic analysis and Ethnograph qualitative software. Mental models of HIV vaccines included live virus, side effects, complete protection (100% efficacy, lifetime protection, reduced anxiety about HIV/AIDS), and "high-risk groups." HIV vaccine risk communication to counter undue fears of vaccine-induced infection and side effects and to mitigate exaggerated expectations of a "magic bullet" may be vital to the effectiveness of first-generation HIV vaccines in controlling the AIDS epidemic.