DescriptionSexual minorities consistently have been shown to be at greater risk for mental health problems and nonsuicidal self-injury (NSSI) behaviors, and this increased risk appears caused by both general psychological risk factors and sexual minority stressors. Most past research on NSSI in sexual minorities, however, has focused on youth populations and has studied general psychological risk factors and sexual minority stressors separately. The current study fills these gaps in the literature by examining NSSI in a sexual minority adult population, examining both general mental health variables and sexual minority stressors together in their relationship to NSSI. 388 adults, 303 of whom were sexual minorities, completed a computerized task to measure internalized homophobia as well as a variety of questionnaires about NSSI, mental health difficulties, and experiences of sexual minority stress. Results found that sexual minority adults were significantly more likely than exclusively heterosexual adults to have engaged in NSSI, to have higher levels of NSSI behaviors, to experience higher levels of mental health problems (such as depression and emotion dysregulation), and to experience higher levels of sexual-orientation-based discrimination. Similarly, self-injuring sexual minority adults reported higher levels of mental health problems than non-self-injuring sexual minority adults. Regression analyses revealed that mental health problems predicted lifetime NSSI behaviors in sexual minority adults, but that sexual minority stressors did not. These findings suggest that NSSI remains a significant problem into adulthood for sexual minorities and that addressing general mental health problems via clinical intervention and prevention programs might work to decrease this population's increased risk.