Despite increased attention to the human rights of those with mental illness, people with psychiatric illness continue to be stigmatized (Gerlinger et al., 2013; Link, Struening, Rahav, Phelan, & Nuttbrock, 1997). The Surgeon General of the United States identified stigma as “the most formidable obstacle to future progress in the arena of mental illness and health” (Satcher, 1999). The deleterious effects of labeling someone with mental illness are pervasive and widely acknowledged (Ben-Zeev, Young, & Corrigan, 2010), and mental illness stigma has been associated with discrimination in multiple systems (e.g., education, housing, work-force, health, mental health, judicial) (Link et al., 1997; Ben-Zeev et al., 2010). One gap in the literature on mental illness stigma concerns the extent to which it influences the sexuality and sexual behaviors of people with psychiatric disorders, important but overlooked factors in achieving a person’s full potential for recovery (Kelly & Deane, 2011; Maj, 2011). Though mental illness stigma has been described as a contributor to social and sexual isolation (Wright & Gayman, 2005; Wright, Wright, Perry, & Foote-Ardah, 2007), recent evidence suggests that it also may increase sexual risk behaviors (Elkington et al., 2013; Elkington et al., 2010). Because the majority of people in psychiatric care worldwide are sexually active and people with mental illness have sharply elevated rates of HIV infection compared to the general population in most regions where they have been examined (Guimaraes, McKinnon, Campos, Melo, & Wainberg, 2010; Meade & Sikkema, 2005), studies of the ways in which mental illness stigma impinges on the sexuality and sexual behaviors of people with psychiatric illnesses have emerged. Among 92 women with mental illness in New York City, experiences of discrimination due to skin color, ethnicity, sexual orientation, drug use, gender, and mental illness were associated with having a casual or sex-exchange partner. These women reported believing that having a mental illness restricted their opportunities in romantic relationships and this belief was associated with having a greater number of sexual risk behaviors (Collins et al., 2008). In a qualitative study in Brazil, mental illness stigma interfered with the ability of sexually active adults in psychiatric care to choose their sexual partners and negotiate safer sexual behaviors (Wainberg, Alfredo Gonzalez et al., 2007). In a sample of 98 adults in psychiatric outpatient settings in Rio de Janeiro, those who reported greater mental illness sexual stigma were significantly more likely to have unprotected sex and significantly less likely to have reduced the number of their sexual partners as a way to protect themselves from HIV (Guimaraes et al., 2010); being male and having greater symptom severity were associated with greater sexual stigma. These studies provide evidence that people with mental illness experience and often internalize stigma related to romantic and sexual relationships and that this stigma is associated with sexual risk behaviors. Building upon these findings, we examined the associations between stigma experiences related to sexuality, psychiatric condition, and gender among 641 people in psychiatric outpatient care in Rio de Janeiro, Brazil. We applied modified labeling theory (Link & Phelan, 2001), which posits that stigma influences behavior through social environmental and social psychological processes. Once labeled and associated with the negative stereotypes of an undesirable trait such as mental illness (societal stigma), the person with that trait experiences stigma via three mechanisms: 1) individual discrimination in which a ‘stigmatizer’ engages in overt practices of discrimination against the stigmatized individual (overt acts by individuals); 2) structural discrimination in which institutional practices work against the stigmatized group (practices and policy); and 3) social psychological processes that involve the stigmatized person’s own perceptions of the negative stereotypes attributed to the undesirable trait (internalized stigma, self-devaluing), and expect discrimination (Link, Cullen, & Struening, 1989). Expectations of rejection can lead to reduced confidence, constricted social networks, depression, and low self-esteem (Link et al., 1997; Wainberg, Alfredo Gonzalez et al., 2007; Link et al., 1989; Rosenfield, Vertefuille, & McAlpine, 2000). We describe the role of gender and of having a severe mental illness diagnosis in sexual stigma experiences through previously described stigma mechanisms. We expected that people with severe mental illness (i.e., schizophrenia, schizoaffective disorder, bipolar disorder, major depression with psychotic features and psychosis not otherwise specified) would show higher scores for all three stigma mechanisms than those without severe mental illness, and that men would experience greater sexual stigma than women (Elkington et al., 2010).