Objective: The majority of people in psychiatric care worldwide are sexually active, and studies have revealed sharply elevated rates of HIV infection in that group compared with the general population. Recovery-oriented treatment does not routinely address sexuality. We examined the relationship between gender, severe mental illness diagnosis, and stigma experiences related to sexuality among people in psychiatric outpatient care. Method: Sexually active adults attending 8 public outpatient psychiatric clinics in Rio de Janeiro (N = 641) were interviewed for psychiatric diagnosis and stigma experiences. Stigma mechanisms well-established in the literature but not previously examined in relation to sexuality were measured with the Mental Illness Sex Stigma Questionnaire, a 27-item interview about stigma in sexual situations and activities. Results: Experiences of stigma were reported by a majority of participants for 48% of questionnaire items. Most people reported supportive attitudes toward their sexuality from providers and family members. Those with severe mental illness diagnoses showed greater stigma on individual discrimination and structural stigma mechanisms than did those with nonsevere mental illness diagnoses, whereas there was no difference on the social psychological processes (internalized stigma) mechanism. Regardless of diagnosis or gender, a majority of participants devalued themselves as sexual partners. Conclusions and Implications for Practice: Adults in psychiatric outpatient care frequently reported stigma experiences related to aspects of their sexual lives. From the perspectives of both HIV prevention and recovery from mental illness, examinations of the consequences of stigma in the sexual lives of people in psychiatric care and improving their measurement would have wide applicability.