This study examined diversity course influence on student prejudice against lesbians and gay men, awareness of heterosexual privilege, and support for gay marriage. The study included heterosexual female students in psychology of women, introduction to women's studies, and nondiversity psychology courses. Students in diversity courses expressed increased heterosexual privilege awareness and support for same-sex marriage across the semester compared with no changes among the nondiversity course students. Although diversity course students also exhibited reduced prejudice against lesbians and gay men, the changes did not differ significantly from students in comparison courses. (Contains 2 tables.)