Background: Out of School Hours Care (OSHC) offers structured care to elementary/primary-aged children before and after school, and during school holidays. The promotion of physical activity in OSHC is important for childhood obesity prevention. The aim of this systematic review was to identify correlates of objectively measured physical activity and sedentary behaviour in before and after school care. Methods: A systematic search was conducted in Scopus, ERIC, MEDLINE (EBSCO), PsycINFO and Web of Science databases up to December 2021. Study inclusion criteria were: written in English; from a peer-reviewed journal; data from a centre-based before and/or after school care service; children with a mean age < 13 years; an objective measure of physical activity or sedentary behaviour; reported correlations and significance levels; and if an intervention study design these correlates were reported at baseline. Study quality was assessed using the Office of Health Assessment and Translati