The physical education (PE) system is a consequential social determinant of pediatric health and well-being. Granting selective achievements, sub-optimal PE outcomes for school-aged children as well as teachers necessitate improvement models and redesign initiatives. This agenda depends on knowledge about the malleable social determinants of the PE system, particularly social-institutional reproduction dynamics, occupational socialization, and public policy. Theoretical propositions and their corollaries lend structure to discipline-specific and interdisciplinary research and development agendas. Pediatric researchers from Kinesiology and Public Health are essential contributors, particularly as social-ecological models gain traction, physical activity discourses replace PE's, and interest resides in whether and how children's participation extends beyond schools and stretches into adulthood.