Limited empirical evidence is available about preschoolers’ sedentary behavior (SB) and physical activity (PA) patterns in Head Start programs, we explored (a) preschoolers’ SB and PA patterns (ranging from SB to light-moderate-vigorous physical activity [LMVPA]) and (b) their relationships with sociodemographic factors, weight status, and motor development. Participants included 216 preschoolers (Mage = 4.32 ± 0.63; girls 56.5%) from six Head Start centers in an urban area in the southwestern region of the United States, assessing Actical activity monitor-based PA, weight status, and motor development. The findings revealed preschoolers who were female, Hispanic/Latinx, with an at risk weight level, and/ or in the below average motor development group tended to engage in less MVPA/LMVPA and also had higher SB patterns while participating in the Head Start program (p < 0.05–0.001, d ranged from 0.23 to 0.62). Head Start stakeholders (e.g., policymakers, leaders, curriculum coordinators, health professionals, and teachers) need to acknowledge the PA and health disparities, and intervene in underserved preschoolers’ health-promoting behaviors. (author abstract)