Policies to improve school progression and reduce the numbers of children dropping out of school are critical if Universal Primary Education (UPE) is to be achieved. This background paper for the UNESCO GMR team draws on a range of resources to provide a synthesis on drop out. The paper focuses on patterns of participation, age-specific drop out rates, equity in drop out rates, and the link between over age enrollment and drop out rates. The paper outlines the main causes of drop out and provides two country case studies, Ghana and Tanzania, to highlight the potential strategies that could be used to address drop out. The paper concludes with our main policy messages.