A student's socioeconomic status (SES) has a significant relation to their academic achievement. Much of this work has explored this in math and reading, but less is known about how SES relates to science achievement, particularly in the early grades. Using quantile regression with nationally representative data, we explored this relation in 12,676 kindergarten students (51.2% boys, 52.2% White, 21.8% Hispanic, 12.7% Black and 6.6% Asian) and 10,339 fifth-grade students (51.3% boys, 49.4 White, 27.2% Hispanic, 9.4% Black and 8.2% Asian). We found less variability in science achievement scores for those high on SES than those low on SES. The scores of the high SES students cluster together on the high end of science achievement, whilst those from low SES score across the distribution. These findings highlight the need to explore what can mitigate the relation between SES and science achievement and where resources to support science achievement are most needed.