Identifying early precursors of body mass index (BMI) and sports participation represents an important concern from a public health perspective and can inform the development of preventive interventions. This article examines whether kindergarten child self-regulation, as measured by classroom engagement and behavioral regulation, predicts healthy dispositions in fourth grade. To address this objective, secondary analyses were conducted using prospective-longitudinal data from 966 children followed by the Quebec Longitudinal Study of Child Development. Self-regulatory skills, including classroom engagement and behavioral regulation, were measured by kindergarten teachers. Greater self-regulatory skills predicted lower BMI and greater parent-reported child sports participation, after controlling for a number of potentially confounding child and family characteristics. This article suggests that assessing kindergarten self-regulatory capacities may help identify children at risk of developing unhealthy dispositions and behaviors in middle childhood.