Between 1970 and 2000, the U.S. high-school graduation stagnated while in many other Organization for Economic Co-operation and Development (OECD) countries it rose markedly. By 2000, the high school graduation rate in the United States ranked 13th among the 19 OECD countries for which comparable data are available. Evidence from two independent sources now shows that the United States high school graduation rate increased substantially between 2000 and 2010. The improvements were especially pronounced among blacks and Hispanics. Between 2000 and 2010, the overall trend changed. The U.S. high school graduation rate increased by 6 percentage points, a substantial shift in a relatively short period of time. The rate of growth over the decade was quite steady. Yet despite these encouraging trends, substantial graduation rate gaps along lines of race, income, and gender persist. Moreover, graduation rates in other OECD countries also increased in the past decade. As a result, the U.S. high school graduation rate in 2010 was still below the OECD average. This article discusses the possible explanations for patterns in American graduation rates.