This synthetic review aims to unite a seemingly disjoint collection of studies over the past 3 decades around their shared examination of sexism in an often overlooked U.S. population, namely girls attending private Christian schools. This undertaking reveals substantial harms that I categorize as those of immediacy and potentiality, which are occurring behind the protective wall separating church and state. Contra the majority of philosophers of education and researchers in this area, these studies lead me to argue that the state has the obligation and legal ability to intervene in this private domain. Notably, this study begins to flesh out a notion of educational harm that may be robust enough for state policy making and legal action in private schools. Based on a legalized understanding of sexist harm, I conclude with a detailed analysis of Constitutional provisions and court decisions relative to state intervention and freedom of religious practice. (Contains 9 notes.)