This research investigated social and academic outcomes from single-sex classrooms in a Tasmanian coeducational government primary school. Interviews, observations and surveys formed the basis of the evidence. Teachers, parents and children reported positive benefits from the class organisation, but these differed according to gender. Staff identified increased confidence and higher self-esteem among girls, whereas boys developed increased motivation and more commitment to schoolwork. Teachers and parents noted that boys' accountability and self-discipline improved. Teachers adopted different strategies from those used with mixed-gender classes and gained higher levels of satisfaction from teaching, attributable to increased children's time "on task". Paradoxically, standardised school testing indicated no increase in academic achievements. However, there may be an extended lag between establishing changed social relationships and measurable academic outcomes, suggesting that if the new class structure is to achieve its full potential, it should be established early in primary school and continue to adolescence.