Objective: Prior research on the efficacy of physical education has been conducted in a piecemeal fashion. More specifically, studies typically test a single benefit hypothesized to be associated with physical education (e.g. body mass index [BMI]) while excluding others (e.g. social skills) and not controlling for important confounds (e.g. diet). Such research designs have precluded a comprehensive evaluation of physical education, and may also help explain mixed findings reported in the literature. The purpose of this study, then, was to re-evaluate the efficacy of participation in physical education through a more robust model that considers BMI, academic achievement, self-concept, and social skills while controlling for poor diet and out-of-school activities (i.e. television viewing, sleep, and general activity levels). Design, Setting, and Method: Structural equation modelling (SEM) was conducted on data derived from a sample of 10,210 fifth graders in the Early Childhood Longitudinal Study. Results: Nationwide, 68% of fifth graders participated in physical education one or two days per week. Physical education was positively associated with academic achievement (effect size = 0.10), and negatively associated with both low self-concept (effect size = 0.06) and less healthy food choices (i.e. sugar-sweetened beverages, potatoes, and fast food; effect size = 0.11). However, participation in physical education was not associated with BMI or teacher-reported social skills. Conclusion: Even at the low "'dosages" reported, physical education is associated with improved mental health, dietary choices, and academic achievement.