An oft-repeated finding in child development research is that height and cognitive ability are positively related. Much of this work is limited in its ability to track height and cognitive development over time, with key constraints being the availability of longitudinal data and measures of ability that are comparable over time. This study evaluates the associations between height and assessments of reading, math, and science in a representative sample of US schoolchildren followed from kindergarten through fifth grade. Associations between height and assessment scores at each grade level, and height-growth and changes in scores over grade levels, are examined. The results suggest modest associations between concurrent height and assessment scores at each grade level that are robust to socioeconomic and school controls. There is limited association between height-growth and assessment outcomes, which is shown only for females. There is also little indication that height or height-growth is associated with improvements in scores. The findings suggest a modest association between height and cognitive ability in contemporary US schoolchildren, being attributed mostly to growth before kindergarten. The findings are consistent with the view that social and biological forces in early-life facilitate both physical and cognitive development.