Background: Twenty-four hour movement behaviors (ie, physical activity [PA], screen time [ST], and sleep) are associated with children’s health outcomes. Identifying day-level contextual factors, such as child care, that positively influence children’s movement behaviors may help identify potential intervention targets, like improving access to child care programs. This study aimed to examine the between- and within-person effects of child care on preschoolers’ 24-hour movement behaviors. Methods: Children (N = 74, 4.7 [0.9] y, 48.9% girls, 63.3% White) wore an Axivity AX3 accelerometer on their nondominant wrist 24 hours per day for 14 days to measure PA and sleep. Parents completed surveys each night about their child’s ST and child care attendance that day. Linear mixed effects models predicted day-level 24-hour movement behaviors from hours spent in child care. Results: Children spent an average of 5.0 (2.9) hours per day in child care. For every additional hour of child care above their average, children had 0.3 hours (95% CI, −0.3 to −0.2) less ST that day. Between-person effects showed that compared with children who attended fewer overall hours of child care, children who attended more hours had less overall ST (B = −0.2 h; 95% CI, −0.4 to 0.0). Child care was not significantly associated with PA or sleep. Conclusions: Child care attendance was not associated with 24-hour PA or sleep; however, it was associated with less ST. More research utilizing objective measures of ST and more robust measures of daily schedules or structure is necessary to better understand how existing infrastructure may influence preschool-aged children’s 24-hour movement behaviors. In addition, future research should consider how access to child care may influence child care attendance.