We compared the sexualities of people with serious mental illness and the general population using the National Health and Social Life Survey (Laumann et al., 1994) and the Indiana Mental Health Services and HIV Risk Study (Wright, 2003). We investigated whether and how the sexual behaviors and relationships of people with serious mental illness differ from the general populations and identified factors differently influencing the organization of sexuality in these two groups. We found evidence that the relationships of people with serious mental illness are characterized by less intimacy and commitment than those of the general population. Additionally, although people with serious mental illness use condoms more consistently, they are also more likely to have concurrent relationships and tend to have sex sooner with new partners, which may contribute to a higher risk of contracting HIV. Our findings point to a need for a paradigm shift in the way that clinicians and researchers conceptualize and manage client sexuality. A less individualistic approach that takes into consideration the relationship context and social and institutional constraints is needed.