This study examined parental attitudes about gender nonconformity in children's books in a sample of parents with children ages 4 to 11. This research sought to understand parental demographic identities associated with attitudes regarding children's books about gender nonconformity, as well as conversations with children about gender nonconformity more broadly. Participants were asked to assess their attitudes toward each of a series of books that either did or did not discuss gender-nonconforming children. Specifically, they were asked about their child reading each book, children in general reading each book, having each book in their child's library, and having their child's teacher teach the book in the classroom. Overall, parents had more negative attitudes toward books about gender nonconformity than about control books that were not about gender. Parents also had the most negative attitudes about teaching books about gender in the classroom. Associations were found between parental attitudes toward gender nonconformity and political affiliation and ideology, religiosity, and age of parent. Republican-identifying parents and those who had more conservative political ideologies reported more negative attitudes toward gender nonconformity books, as well as more negative attitudes about exposing children to gender nonconformity overall. Parents who rated themselves as committed to religious teachings and those who noted that they were more religious also had more negative gender nonconformity book attitudes and overall gender attitudes, although these effects did not hold when controlling for political ideology. Older parents also had more negative gender nonconformity book attitudes and overall gender attitudes. The findings of this study may have implications for educating parents about the impact of gender nonconformity books.