Background/Context: Scholars have attributed the underperformance of U.S. students relative to students in other high-income countries to unequal access to high-quality educational environments. Poor students are presumed to do disproportionately worse on international achievement tests and, consequently, to pull down the U.S. average. Conversely, high-socioeconomic-status (SES) students in the United States, who are among the wealthiest in the world, are presumed to outperform other rich students. Purpose/Objective/Research Question: Despite these common assumptions regarding the performance of different SES groups in the United States, little research has empirically examined the extent to which these assumptions are correct. As such, we seek to benchmark low-, middle-, and high-SES students in the United States relative to comparable groups in other countries in order to contextualize U.S. performance. Data Analysis: We analyze 2012 Programme for International Student Assessment (PISA) mathematics achievement for 42 high-income countries. We average scores for low-, middle-, and high-SES groups within each country, using PISA's index of economic, social, and cultural status (ESCS) index to generate categories. We then generate grand means for all countries in our sample to have an overall benchmark for each group. To calculate overall country scores and SES group scores, we use PISA-specific plausible values techniques. We use 12 points to identify meaningful achievement differences. Findings/Results: Contrary to conventional wisdom regarding the performance of students in the United States on PISA, poor students do not disproportionately pull down U.S. scores; relative to poor students around the world, poor students in the U.S. are average, despite being among the most socioeconomically disadvantaged. Moreover, and contrary to conventional wisdom, the richest students in the United States do not exhibit stellar performance and are average compared with other rich students globally, despite being among the richest in the world. Middle-SES students in the United States, however, perform 17 points below the average for all middle-SES students in the 42 countries we examined, suggesting that they are nearly half a school year behind middle-SES students around the world. Conclusions/Recommendations: Although common explanations for U.S. PISA achievement may seem logical, they are not always correct. Such incorrect assumptions overlook significant educational concerns that could be shaping educational policies. Considering our findings, the United States needs to address the within-country SES-based achievement gap, but it also needs to address the gap between the United States and other countries. While policy makers should continue to focus on economically disadvantaged students, there are systemic concerns with the U.S. education system that prevent the academic success of students across the class spectrum.