Research indicates that antigay bias follows a specific pattern (and probably has throughout written history, at least in the West): (a) men evince more antigay bias than women; (b) men who belong to traditionally male coalitions evince more antigay bias than those who do not; (c) antigay bias is targeted more at gay men than at lesbians; and (d) antigay bias is targeted more at effeminate gay men than at masculine gay men. We propose the coalitional value theory (CVT) of antigay bias to explain this pattern. The CVT argues that men evolved psychological systems to facilitate coalitional formation and regulation and that these systems may lead to antigay bias because men perceive gay men as possessing lower coalitional value for traditionally male coalitions. We tested the CVT in 4 studies. In Study 1, gay men were perceived as less masculine than straight men and as less competent at traditionally masculine activities. In Studies 2 and 3, masculine gay men were rated as more competent than and chosen over feminine straight men in traditionally masculine activities. In Study 4, actual coalitional contribution predicted men’s perceptions of other men’s derogation more than did sexual orientation. We also found that men’s preferences for masculinity diminished in nontraditionally masculine tasks such as poetry, suggesting that men’s assessments are contingent upon the nature of the task. This offers a possible palliative for antigay bias: coalitional pluralism, which we discuss.