Attribution theory suggested the hypothesis that heterosexuals' attitudes toward persons bearing the social stigma of homosexuality would be more negative when homosexuality was attributed to controllable than to uncontrollable causes. It was further hypothesized that groups that have been found to express more favorable attitudes toward lesbians and gay men -persons rating other-sex gay people and those who know a gay person-would attribute homosexuality to less controllable causes. Data from 193 female and 173 male heterosexual college students supported the first, but not the second, hypothesis. In addition, heterosexual women were more likely to report knowing a lesbian than heterosexual men were to report knowing a gay man, and among respondents who reported knowing a gay man, women reported closer acquaintanceship than men did. The implications of these findings for changing antigay attitudes are discussed.