Background: Few school settings offer opportunities for preschool children to engage in structured physical activity, and only a few studies have been conducted examining exergaming's effectiveness on health outcomes in this age group. This study's purpose, therefore, was to examine a school-based exergaming intervention's effect on preschool children's perceived competence (PC), motor skill competence (MSC), and physical activity versus usual care (recess), as well as to examine gender differences for these outcomes. Methods: A total of 65 preschool children from 2 underserved urban schools were assigned to 1 of 2 conditions, with the school as the experimental unit: (1) usual care recess group (8 weeks of 100min of recess/week (5 days × 20 min)) and (2) exergaming intervention group (8 weeks of 100min of exergaming/week (5 days × 20 min) at school). All children underwent identical assessments of PC, MSC, and moderate-to-vigorous physical activity (MVPA) at baseline and at the end of the 8th week. (author abstract)