The Education Millennium Development Goal of universal primary education (UPE) states that "by 2015, children everywhere, boys and girls alike, will be able to complete a full course of primary schooling." The 2008 midterm Global Monitoring Report claims that "A country's distance from UPE appears most clearly in terms of the net enrollment ratio (NER), the share of children of official primary school age who are actually enrolled in primary schools." This assumes that the share of those enrolled accurately reflects the share who will eventually complete a full course of primary schooling. For many countries, this assumption does not hold. I examine "on-track" sub-Saharan African countries, comparing progress toward UPE as measured by (1) the NER and (2) the primary school completion rate (PSCR). These measures can produce dramatically different indications of the amount and nature of progress achieved over time. I discuss why these differences occur. Finally, I argue that the PSCR, in the context of the proximate determinants of educational attainment framework, provides an integrated, mathematically coherent perspective on progress toward UPE and useful feedback for policy makers.