 This systematic review found that physical activity is strongly linked to positive health outcomes in young children. It showed that specific types of physical activity, total physical activity and physical activity of at least moderate to vigorous intensity are consistently associated with multiple health indicators. The majority of evidence was in preschool age children, three to four years old. These findings will help inform evidence-based guidelines on physical activity for young children. This article was authored by Valerie Carson, Un Young Lee, Lindell Hewitt and others.