Youth physical activity (PA) levels are a central focus for physical educators and health professionals worldwide. This study (a) examined the PA levels of children during structured and unstructured PA lessons of an after-school program (ASP) and (b) described the children's perceptions of structured and unstructured PA. Participants were 31 children, Mage (10.37 [plus or minus] 1.4 yrs.), BMI percentile (79.86 [plus or minus] 28.01), who actively participated in an ASP. Activity measurements examined mean steps per minute, percentage of MVPA, and percentage of activity time during unstructured and structured PA opportunities. Children accumulated higher mean steps per minute and percentage of activity time during unstructured PA; however, they had a higher mean percentage of MVPA during structured PA. There were statistically significant differences between mean steps per minute and mean percentage activity time. The findings suggest that implementation of forms of unstructured PA may increase the daily PA of youth and help them to meet recent national recommendations. (author abstract)