Little scientific attention has been paid to bisexuality or to societal attitudes about bisexual people. Often, biphobia has been assumed to be identical to homophobia. In this study, 229 heterosexual undergraduate students rated their degree of agreement to stereotypical statements about bisexuality and provided information on their attitudes about the acceptability of bisexual, gay, and lesbian people. Although there was a high degree of correlation between biphobia and homophobia, negative attitudes about bisexuals, men in particular, were more prevalent than negative attitudes about lesbians or gay men. Biphobia and homophobia should be considered related, but distinct, phenomena.