Psychosocial variables influence physical activity for different age groups, sex, and ethnic groups. However, little is known about their influence on physical activity in preadolescent Latino children. The authors examined how a) confidence in one's ability to be physically active (self-efficacy); b) ideas about the consequences of being physically active (beliefs), and c) the influences of family and friends on physical activity (social influences) effect physical activity levels in overweight (body mass index >or=85%) Latino preadolescent children. One hundred and fourteen preadolescents participated in a larger intervention designed to improve healthy lifestyles for Latino families. The authors report baseline data collected at a community-based primary care clinic. Multivariate regression analyses showed that only social influences significantly predicted (P < .01) the metabolic equivalent adjusted self-reported baseline physical activity. Prevention and intervention strategies that augment social influences on physical activity are likely to result in more physical activity and improved health in these children.