The introduction of single-sex classes within co-educational schools is a strategy adopted by some schools to enhance the learning experiences of either the girls or the boys depending upon the educational climate of the time. In a period dominated by the 'what about the boys?' debate, this strategy is currently being introduced and advocated in a number of schools in an attempt to raise boys' achievement. This article explores the value of introducing single-sex classes within co-educational schools, and in doing so, it draws upon the perspectives of girls and boys involved in one such initiative. The article concludes that girls-only classes may have positive effects for girls. However, curriculum-as-usual boys' classes do nothing to challenge the problematic macho male cultures inherent in schools; indeed, it may be the case that they actually exacerbate them.