In recent years, HIV prevention efforts among gay men in the US have broadened in scope to incorporate the social, cultural,interpersonal, and contextual factors associated with HIV infection and transmission. Findings from a recent study that supports incorporating these factors show that an examination of relationship dynamics is needed to help explain higher rates of HIV among young Black and Latino gay men since factors such as the number of sexual partners, specific sexual behaviors, and drug use did not explain their higher rates of HIV infection relative to White men. The Principal Investigator (PI) of the proposed research and her team have been examining relationship dynamics associated with HIV risk among gay couples for the past five years. Their initial study, which is ongoing, was designed to be broad in scope to both capture the breadth of variables in gay male relationships and how these variables are associated with HIV risk. One variable of interest is the power differentials that may exist between partners in a relationship. Scale instruments that are currently available to detect and measure power differentials were developed for heterosexual couples only and are therefore limited in their applicability to gay male couples. In the PI’s ongoing study, one of the existing scales, the Sexual Relationship Power Scale (SRPS), was modified and adapted for use. We found that certain dimensions of relationship power (e.g., power in decision-making, lack of power about barebacking, and power in condom negotiation) are associated with HIV risk in a manner similar to many other relationship factors. Although the adapted SRPS scale lent some insight into the power dynamics at work within gay male relationships, it remains unclear what role race plays and how it may affect HIV risk. What is clear, however, is that Black and White MSM make up the largest proportion of HIV infections in the US. Yet, we know very little about race in gay male relationships. When one considers couple HIV status (i.e., the HIV status of both partners in the relationship), another layer of complexity emerges. For example, concordant negative couples have different experiences and expectations than discordant couples. Recognizing the crucial association of relationship power with HIV risk among gay couples and the dearth of research on it, we propose to conduct a comprehensive mixed-methods study to understand and define the dimensions of relationship power among Black, White and biracial Black and White couples (hereafter referred to as biracial B&W couples) who are HIV concordant negative or discordant. An important component of this effort will involve the development and testing of a comprehensive quantitative scale to measure dimensions of relationship power in gay male couples. Following this, we want to study the associations of the different dimensions of relationship power with HIV risk and known psychosocial correlates of HIV risk (e.g., relationship satisfaction, agreement investment, social support, and experiences of racism and homophobia) In the future we hope to expand the cultural and racial component of the scale and apply it Latino and Asian gay couples. Including them at this time is beyond the scope of one study. We envision all of this research as leading to the development of an empirically based HIV prevention trial for gay male couples in the US.