This study examined whether associations exist between PA intensity, self-regulation, and indicators of school readiness, a proxy for academic achievement, in young children. Thirty young children completed assessments of physical activity, school readiness indicators, and self-regulation. Physical activity intensity was classified as light, moderate or vigorous. School readiness indicators were assessed using expressive and receptive subtests. There were no associations between light and moderate physical activity, school readiness indicators, and self-regulation. Additionally, there was no association between vigorous activity and the receptive subtest of the school readiness indicators. Correlations were significant between vigorous activity, self-regulation, and expressive subtest. School indicator expressive scores and self-regulation were significantly predicted by the level of vigorous activity. Results suggest the existence of an intensity threshold influencing the PA, self-regulation, and school readiness association.