Previous research has documented that sexual minorities are more likely than heterosexual people to experience mental health problems, but little is known about how these disparities emerge. Analysis of data from Miami-Dade County, Florida, shows that young adults reporting same-sex contact have higher levels of depressive symptoms and drug use than those without such contact, but that different processes explain the disparities in the two outcomes. A substantial portion of the gap in depressive symptoms is explained by sexual minorities' higher levels of stress exposure and their lower levels of family support and psychological resources. The gap in drug use is not explained by these processes, but is partially explained by self-exploratory attitudes and permissiveness of drug use in social networks. This study highlights the importance of using multiple outcome measures in research that examines mechanisms underlying mental health disparities across social groups. (Contains 3 notes and 3 tables.)