Children of active parents tend to be more active. This Digest describes the various socialization factors that influence a child's interest and involvement in physical activity. While role modeling exerts some effect, recent research suggests that the nature of parental influence may be much more complex. A useful theoretical model to explain parental influence on physical activity is the expectancy-value model of Eccles and Harold (1991). The model explains parent socialization behaviors related to sport and physical activity. There are various ways that parents can socialize their children to be physically active, including using parental encouragement, parental involvement, parental facilitation, and parental role modeling. Declining levels of physical activity exert a major influence on the increasing levels of childhood obesity. It is important for children to begin developing healthy activity patterns early in life. Because activity patterns have been found to track over the lifespan, efforts to promote physical activity at a young age can have major long-term public health benefits. (Contains 16 references.) (SM)