Over the past decade, the OECD Programme for International Student Assessment (PISA) has become the world's premier yardstick for evaluating the quality, equity and efficiency of school systems. This chapter introduces PISA and sets the scene for situating the PISA performance of 15-year-olds in the United States against global patterns and trends. Results from the OECD's recent Survey of Adult Skills (OECD, 2013a) show that highly skilled adults are twice as likely to be employed and almost three times more likely to earn an above-median salary than poorly skilled adults. In other words, poor skills severely limit people's access to belter-paying and more rewarding jobs.