Despite their prominence in civil rights movements, out-group allies have been understudied. The current research examined out-group alliance, focusing on predictors of heterosexuals' advocacy for lesbian, gay, bisexual, and transgender (LGBT) rights. Heterosexuals who were recruited through an online panel of research participants completed a survey containing measures of empathy, out-group contact, gender, education, and attitudes toward gays and lesbians. Additionally, participants indicated whether they had engaged in several allied behaviors (e.g., donating money for LGBT causes). Women, educated individuals, and those with gay and lesbian friends were more likely to be allies. Additionally, alliance was greatest among individuals lower in prejudice and simultaneously higher in positivity toward gays and lesbians. Implications regarding intergroup relations and future research are discussed.