Some past work indicates that sexual minorities may experience impairments in social health, or the perceived and actual availability and quality of one’s social relationships, relative to heterosexuals; however, research has been limited in many ways. Furthermore, it is important to investigate etiological factors that may be associated with these disparities, such as self-reported discrimination. The current work tested whether sexual minority adults in the United States reported less positive social health (i.e., loneliness, friendship strain, familial strain, and social capital) relative to heterosexuals and whether self-reported discrimination accounted for these disparities. Participants for the current study (N = 579) were recruited via Amazon’s Mechanical Turk, including 365 self-identified heterosexuals (105 women) and 214 sexual minorities (103 women). Consistent with hypotheses, sexual minorities reported impaired social health relative to heterosexuals, with divergent patterns emerging by sexual orientation subgroup (which were generally consistent across sexes). Additionally, self-reported discrimination accounted for disparities across three of four indicators of social health. These findings suggest that sexual minorities may face obstacles related to prejudice and discrimination that impair the functioning of their relationships and overall social health. Moreover, because social health is closely related to psychological and physical health, remediating disparities in social relationships may be necessary to address other health disparities based upon sexual orientation. Expanding upon these results, implications for efforts to build resilience among sexual minorities are discussed.