This study investigated possible cultural differences in the association of power, authentic self-expression, and well-being within romantic relationships. Participants (N = 314) included European American students from a central Texas university and Mexican American students from a border university. Results indicated that power inequality was associated with a lack of authentic self-expression among men and women in both populations, although a three-way interaction between sex, culture, and power indicated that Mexican American men responded differently than other groups. Results also indicated that a lack of authenticity negatively impacted psychological health, especially for Mexican Americans. Findings suggest that authentic self-expression is one of the primary ways in which power inequality impacts close interpersonal relationships, and that gender and cultural variables must be examined simultaneously when considering the link between power and authenticity.