Children's wellbeing has been of utmost concern to society, and recently this topic has taken a particular focus in both health and achievement. As the focus shifts towards promoting a healthier and more academically successful youth, the relationship between the two warrants investigation. Specifically, the relationship between physical fitness and academic performance (i.e. grades) in 4th grade students was assessed. A cross-sectional design was used to assess physical fitness of children (M=9.39 years) by means of the FITNESSGRAM assessment tool. Third-quarter grades were used to measure academic performance. Relationships between the variables were determined through bivariate plots, Pearson product moment correlation analysis, independent t-tests, and a three-step regression analysis. The results show a significant relationship between students' aerobic fitness and academic performance. Furthermore, the findings of this study suggest incremental validity between aerobic fitness and academic performance, thus implying predictive value associated with increased physical fitness and academic achievement.