Physical activity (PA) engagement in Early Childcare and Education Centers (ECEC) supports preschoolers' ability to meet the national physical activity guidelines. However, the influence of Head Start playground quality, as assessed by the Head Start Body Start Play Space Assessment (PSA), on Head Start preschoolers' school day PA is under-researched. This study examined (1) the relationship between PSA quality scores and Head Start preschoolers' school day PA engagement and (2) the association between PSA quality scores and the likelihood of preschoolers' meeting the national PA guidelines during Head Start hours. Head Start preschoolers (N = 240, Mage = 3.9 years, 47% boys) from three centers participated in the study. Playground quality was assessed using the PSA, and preschoolers' PA during Head Start was measured using wrist-worn GTX3 Actigraph accelerometers. Approximately, 77% of preschoolers in this sample achieved the recommended amount of PA per hour (15 min), over 90% accumulated 60 min of MVPA, and half surpassed 180 min of total PA during Head Start hours, and preschoolers' PA engagement differed based on child sex and Head Start center attended. PSA playground quality scores were not significantly related to the amount or intensity of preschoolers' PA engagement or the likelihood of meeting the national PA guidelines during Head Start. However, our findings revealed unique PA patterns among Head Start boys' and girls' PA that should be probed in the future studies using the PSA.