This cross-sectional study measures decoding and fluent reading skills of a random sample of 250 first- through third-grade students attending a high-SES school. Growth was compared between proficient and struggling readers with results showing the latter group significantly behind their higher attaining peers on all measures. When student attainment was compared to national norms, results revealed that students entering first grade as high-attaining had declined to average or below by the end of third grade, while the struggling reader group consistently lagged behind their proficient peers. These outcomes show that it is possible for high-attaining students to lose the advantage provided by their high-SES background.