Despite continued high HIV risk among Hispanic men who have sex with men (HMSM), culturally tailored, theoretically based interventions have yet to be developed and tested. As a first step toward intervention development, we collected quantitative and qualitative data on sociocultural and psychological factors associated with drug use and risky sex among 566 HMSM recruited from community and Internet venues. Participants reported high rates of drug use (43%), unprotected anal sex (45%), and multiple sex partners (median 4) in the past 6 months. In multivariate analyses, use of drugs was associated with HIV seropositivity, less orientation to the Hispanic community, stronger attachment to the gay community, lower levels of homophobia, higher numbers of sex partners and more unprotected anal sex. The need for acceptance and desire to please partners emerged as core drivers of HIV risk in the qualitative data. Findings were used to guide development of Proyecto SOL, a theoretically grounded intervention that targets core determinants of HIV risk, builds on protective cultural influences, and strengthens positive social connections.