Research suggests that a country does not need inequity to have high performance. However, such research has potentially suffered from confounders present in between-country comparative research (e.g., latent cultural differences). Likewise, relatively little consideration has been given to whether the situation may be different for high- or low-performing students. Using five cycles of the Programme for International Student Assessment (PISA) database, the current research explores within-country trajectories in achievement and inequality measures to test the hypothesis of an excellence/equity tradeoff in academic performance. We found negative relations between performance and inequality that are robust and of statistical and practical significance. Follow-up analysis suggests a focus on low and average performers may be critical to successful policy interventions.