Book censorship efforts in the USA have become increasingly concerning for champions of freedom of expression and civil liberties. The movement to ban books is seemingly driven by a desire to curtail adolescents' access to information about sexuality and gender diversity. This paper details the findings of a content analysis of the American Library Association's (ALA) Top 10 Most Challenged Books list from 2011 to 2021. The authors analysed purported reasons for book challenges along with target age groups for the 42 books within our sample period. We found that most of the books in the ALA Top 10 list were challenged for reasons related to sexuality and/or LGBTQ themes. Between 2011 and 2015, book challengers were most likely to claim to be motivated by general perceptions of 'sexual explicitness'. However, after 2016, and perhaps as a backlash against the Federal Government's legalisation of same-sex marriage, purported LGBTQ content in books was a stronger motivator. Given that most of the books in the top 10 most challenged list are intended for adolescent readers, our findings have implications for informal sex education and access to information about LGBTQ lives.