In recent years, social scientists have identified not just heterosexism and homophobia as social problems, but also heteronormativity--the mundane, everyday ways that heterosexuality is privileged and taken for granted as normal and natural. There is little empirical research, however, on how heterosexuality is reproduced and then normalized for individuals. Using survey data from more than 600 mothers of young children, ages 3 to 6 years old, this article examines how mothers normalize heterosexuality for young children. The data suggest that most mothers, who are parenting in a gendered and heteronormative context to begin with, assume that their children are heterosexual, describe romantic and adult relationships to children as only heterosexual, and make gays and lesbians invisible to their children. Those who consider that their children could some day be gay tend to adopt one of three strategies in response: Most pursue a passive strategy of "crossing their fingers" and hoping otherwise. A very few try to prepare their children for the possibility of being gay. A larger group, primarily mothers from conservative Protestant religions, work to prevent homosexuality. I conclude by discussing the implications of these findings for understanding sexual identity development and the construction of heteronormativity. (Contains 7 footnotes and 4 tables.)