Childhood overweight and obesity are major public health problems in the United States. Children who experience poverty are 1.5 times more likely to suffer with overweight and 1.6 times more likely to have obesity. The extent to which overweight or obesity exacerbates the negative influence of socioeconomic inequality on child academic outcomes has not yet been examined. We estimated the effect of poverty on math and reading achievement trajectories using the Early Childhood Longitudinal Study (ECLS) Kindergarten class of 1998-1999 survey data and multilevel growth curve modeling techniques. Our findings indicate that the impact of obesity status is more pronounced for children from low socioeconomic backgrounds in both reading and math achievement, as well as for children with overweight in reading achievement scores. Thus, we see evidence that overweight and obesity moderate the pathway through which early-childhood poverty affects school performance. Given that we identified overweight and obesity as putative mechanisms through which socioeconomic deprivation affects academic achievement, focusing on overweight and obesity prevention may alter students' academic trajectories. Taken together, we see evidence that the combined negative effect of increased weight status and poverty, beyond the independent effects of each, has far-reaching consequences for educational outcomes.