Over the past five years, a polarised debate about the potential contribution of low-cost private schools (LCPSs) to achieving Education for All (EFA) objectives has received growing coverage in international policy circles. At the heart of this debate are disputed questions about whether these schools are providing quality education, reaching disadvantaged groups, supporting or undermining equality (including between girls and boys), affordable for the poor and financially sustainable. This topic guide synthesises the best available evidence on these questions, navigating readers through often inconclusive and sometimes contradictory research findings. It examines the main challenges development agencies seeking to understand and support LCPSs have encountered to date, documenting emerging approaches and lessons learnt.