Previous research identifies stark socioeconomic disparities in child injuries, yet research on the repercussions hereof on other aspects of children's lives remains sparse. This paper tests whether social gradients in minor traumatic brain injuries (mTBIs or concussions) contribute to corresponding inequalities in children's academic performance. Previous research on this topic is mostly based on small samples and confounded by non-random selection into experiencing mTBIs. We improve on prior research by using high quality, large N, administrative registry data. Further, we control for selection into having an mTBI via comparing the test score progression of children having an mTBI with children who experience an mTBI in later years (staggered difference-in-differences). Based on Danish ER/hospital records and national test score data, we find that children from families with lower earnings and less education are more likely to experience an mTBI and that having an mTBI negatively correlates with reading test scores. However, comparing present with future mTBI cases, we show that having an mTBI within a year before a test does not negatively affect children's reading scores. Our findings suggest that negative correlations between mTBIs and academic performance more likely reflect socioeconomic gradients in mTBI incidents rather than a direct causal effect. Further, socioeconomic gradients in mTBI incidents do not significantly contribute to corresponding disparities in academic performance.