This paper discusses the basis for differences among heterosexuals in their reactions to gay people, with special emphasis on the issue of gender differences. Three studies conducted with students at six different universities revealed a consistent tendency for heterosexual males to express more hostile attitudes than heterosexual females, especially toward gay men. The same social psychological variables appear to underlie both males’and females’attitudes toward both gay men and lesbians: religiosity, adherence to traditional ideologies of family and gender, perception of friends’agreement with one's own attitudes, and past interactions with lesbians and gay men. The role of these variables in shaping attitudes is discussed and areas for future research are proposed. Construction and validation of the Attitudes Toward Lesbians and Gay Men (ATLG) scale are also described.