This document summarizes the results of the 2009 Program for International Student Assessment (PISA) comparing the performance of 15-year-old students in the United States to students in other participating countries in reading literacy, mathematics literacy, and science literacy. It finds that 18 countries had higher average scores than the US in one or more subjects, while 33 countries had lower average scores. For 13 countries, their students' scores were not measurably different from those of US students.