Sexual minority women (SMW; e.g., lesbian, bisexual) are more likely than heterosexual women to be heavy drinkers, with bisexual women showing the highest risk. There is ample literature demonstrating that intimate relationships protect against stress-related health risk behaviors in the general population. However, very little research has focused on SMW's relationships and far less is known about the relationships of SMW of color. Using intersectionality theory as our framework, we tested two competing models to determine whether the effects of minority sexual identity (lesbian, bisexual) and race/ethnicity (African American, Latinx, White) are: (a) additive, or (b) multiplicative in the associations between relationship status and heavy drinking. Data are from a diverse sample of cisgender SMW (N = 641) interviewed in Wave 3 of the Chicago Health and Life of Women (CHLEW) study, a 20-year longitudinal study of SMW's health. Findings from two-and three-way interactions provide mixed evidence for both the additive and multiplicative hypotheses; support for each varied by sexual identity and race/ethnicity. Overall, we found that Latinx SMW, particularly single and bisexual Latinx SMW, report the highest rates of heavy drinking compared to their cohabiting and lesbian counterparts, respectively. African American single SMW reported significantly higher rates of heavy drinking compared to their cohabiting counterparts. Our findings suggest that the protective qualities of SMW's intimate relationships vary based on sexual identity and race/ethnicity-and the intersections between them. These results highlight that research among SMW that does not take into account multiple marginalized identities may obscure differences.