We used a computer harassment paradigm to test the hypothesis that affirming the legitimacy of discrimination against homosexuals increases the likelihood that heterosexual men will engage inverbal gay bashing. Legitimacy of discrimination was varied among heterosexual males (N ¼167) by suggesting that denying homosexuals rights and benefits is either illegitimate or legitimate, and participants interacted online with either a gay or straight bogus discussion partner. Results show that (a) participants sent more offensive comments when the legitimacy of discrimination against homosexuals was affirmed, and (b) legitimacy affected gay bashing through its effect on collective guilt. These findings suggest that challenging the legitimacy of discrimination can be an effective strategy for reducing outgroup derogation. Copyright # 2010 John Wiley & Sons, Ltd. Anti-gay harassment is both widespread and damaging to the physical and psychological well being of homosexual individuals (Herek, Cogan, & Gillis, 2002). Whilegay bashing can refer to a range of behaviors from telling anti-gay jokes to violent hate crimes, we define gay bashing as verbal denigration based on an individual’s sexual orientation. Importantly, this definition does not require that derogatory remarks be directed toward a gay individual. Heterosexuals making anti-gay comments to other heterosexuals can be considered gay bashing for two reasons. First, the offensive remarks can be experienced as harassment if overheard by a gay individual. Second, derogatory language legitimizes antigay prejudice as normative and reinforces the broader culture of heterosexism (Herek, 1990). Gay bashing and anti-gay prejudice (Herek, 2002; Kite & Whitley, 1996) are more prevalent among heterosexual men than among heterosexual women. Implicit inversion theory (Kite & Deaux, 1987) offers an explanation for this sex difference, suggesting that anti-gay prejudice stems from a perceived violation of gender norms. Previous research shows those who hold more traditional gender role beliefs are more prejudiced toward homosexuals (Kite & Whitley, 1998; Nierman, Thompson, Bryan, & Mahaffey, 2007). Because the male gender role incorporates heterosexuality as an integral part of masculinity, men may engage in gay bashing to assert their own masculinity. In this way, gay bashing serves a social-expressivefunction(Herek, 1987), helping heterosexual men assert their status in a valued ingroup. Thus, there may be important identity-protective motivations for gay bashing. JUSTIFICATION OF DISCRIMINATION