Lesbian, gay, and bisexual (ie, sexual minority) populations have increased prevalence of both self-injurious and suicidal behaviors, but reasons for these disparities are poorly understood. Objective: To test the association between socially based stressors (eg, victimization, discrimination) and self-injurious behavior, suicide ideation, and suicide attempt. Participants: A national sample of college-attending 18- to 24-year-olds. Methods: Random or census samples from postsecondary educational institutions that administered the National College Health Assessment during the Fall 2008 and Spring 2009 semesters. Results: Sexual minorities reported more socially based stressors than heterosexuals. Bisexuals exhibited greatest prevalence of self-injurious and suicidal behaviors. In adjusted models, intimate partner violence was most consistently associated with self-injurious behaviors. Conclusions: Sexual minorities' elevated risks of self-injurious and suicidal behaviors may stem from higher exposure to socially based stressors. Within-group differences among sexual minorities offer insight to specific risk factors that may contribute to elevated self-injurious and suicidal behaviors in sexual minority populations. (Contains 3 tables.)