This study investigated demographic predictors of consistency and change in heterosexual people's attitudes toward homosexual behavior. A nationally representative sample of Australian men and women were recruited via random digit dialling in 2004 through 2005. Participants completed annual computer-assisted telephone interviews over the next five years. Questions about attitudes toward male and female homosexual behavior were assessed at Wave 1 (2004-2005) and Wave 3 (2006-2007) of the study. The majority of the sample reported tolerance of both male and female homosexual behavior (with women slightly more tolerant than men). Multivariate analyses showed that those who regularly attended religious services were more likely to consistently disapprove of homosexual behavior and more likely to change from tolerant to disapproving. Among those who were initially tolerant, younger respondents and those with higher educations were less likely to become homophobic. The results of this study show that individual attitudes toward homosexual behavior are open to change, particularly toward a more tolerant position. Religiosity appears to be consistently associated with the development and reinforcement of homophobic tendencies.