Heterophobia, defined as gay men's fear and avoidance of heterosexual men, has been linked to behavioral health outcomes and could contribute to social disconnectedness and intergroup conflict. The Gay Male Heterophobia Scale assesses 3 meaningful aspects of gay male heterophobia: disconnectedness, expected rejection, and unease/avoidance. The current study sought to assess the development of heterophobia among gay men over 2 weeks using a longitudinal cross-lagged panel design. Using data gathered from 253 gay-identified men collected on MTurk, the results indicated that disconnectedness is an important mediator in the relationship between minority stress and unease/avoidance of heterosexual men but does not mediate the relationship between minority stress and expectations of rejection. Implications for future research and clinical applications are provided, in addition to a discussion of study limitations.