This cross-sectional study documents significant associations between patterns of sexual risk behaviors and psychiatric diagnoses in a multiethnic community sample of young adults (N = 1803) in South Florida. Self-report data regarding sexual behavior and psychiatric symptoms were collected in structured interviews in a follow-up of an earlier school-based study. Cluster analysis was used to group participants with regard to levels of sexual risk behaviors during the past year. Chi-square analysis and ANOVA identified significant associations between cluster membership and (a) lifetime and (b) past year diagnoses for affective disorders, conduct disorder, antisocial personality disorder, alcohol abuse/dependence, marijuana abuse/dependence, and other drug abuse/dependence. In addition, higher levels of sexual risk behaviors were associated with higher levels of cumulative lifetime psychiatric disorders. Implications for selected prevention of sexually transmitted diseases (STDs) and the treatment of psychiatric disorders in young adulthood are discussed.