The retreat to single-sex classes in co-educational comprehensive schools in the UK reflects a long history where educational policy and practice has made explicit the belief that boys and girls are different in how they learn and what they should learn. However, there is also a common assumption that there is equality in what is made available to learn and, if there is not, then single-sex organisation achieves this. The authors challenge this opinion and offer a fresh and theoretically informed look at the debate about single-sex teaching, presenting insights from research about the intended and unintended consequences of gender division in schools. Drawing on classroom observations and in-depth interviews with teachers and students, the book illustrates the effect of single-sex classrooms on learners and on the versions of subject knowledge made available to them. In exploring the differences in teaching practices between boys’ and girls’ classrooms, in relation to subjects such as Science, English, Drama, and Design and Technology, the authors highlight how single-sex teaching can, inadvertently, create circumstances which limit rather than open up students’ access to subject knowledge. The authors offer conceptual tools for investigating the knowledge-gender dynamic, advocating that learning will expand if teachers work with gender to help students to cross boundaries into non-traditional gender territories within subject lessons. Rethinking Single-Sex Teaching is thought-provoking reading for teachers, head teachers, academics and policy makers.