Proponents of character education claim cultivating virtues during schooling helps students, schools and society to flourish. However, critics argue that character education programs implicitly justify social inequality by assuming success or failure in life is due to individuals’ efforts to develop their own characters. However, there is little empirical research about which individual factors, such as gender, or contextual factors, such as school type, may affect secondary school students’ character. This article begins to address this gap by the means of a comparative case study of moral reasoning performance within and between two very different kinds of secondary school in Mexico – a public co-educational school and a private girls’ school. Results suggest that individual differences (gender, religion, family circumstances and socio-economic status) and school (moral education program and school ethos) may relate to students’ ability to make moral judgements in response to realistic moral dilemmas. We consider these findings in relation to ongoing debates about character education worldwide, focusing on how gender, religion and school-type may impact on adolescents’ moral reasoning.