Background: To date, most research investigating the influence of parents on children"s physical activity behavior has been conducted among school-aged children. As a result, we have a limited understanding of the mechanisms through which parents can influence their young children's physical activity behavior. The purpose of this study was to examine the influence of various hypothesized parental influence variables on children's physical activity behaviors. Methods: An on-line survey assessing various hypothesized parental influences and an estimate of the amount of time their child engaged in physical activity behavior was completed by 176 parents. Results: Parents who perceived physical activity to be important for their child, had confidence in providing support for their child's physical activity, had good physical activity experiences as a child, and had high perceptions of their child's physical ability were more likely to employ activity-facilitating parenting practices and behaviors that were associated with their preschool children's physical activity behaviors. Discussion and Translation to Health Education Practice: Parenting practices and behaviors (e.g., parental support for children's activity behaviors) may play an important role in preschool children's physical activity behaviors. Future prospective studies are needed to confirm the findings of the present study. (Contains 4 tables and 1 figure.)