Low-cost private schools (LCPS) are widespread in Kenya, particularly in urban areas. This study examines the reasons that parents send children to fee-charging schools in a context of free public primary education. Drawing on parent survey and interview data, as well as interviews with national policy makers, we found that parents who chose LCPS for their children were more driven by quality concerns than were public school parents. We also present data on the costs of the school types, compared to household income. Despite being termed 'low cost', the fees charged by schools primarily serving the poor were often a heavy burden on families. We conclude with recommendations for maximising the impact of LCPS on educational access and quality.