Childhood obesity is a major public health concern caused in part by decreasing levels of physical activity (PA). Identification of effective population level strategies for increasing children’s PA levels is critical for improving overall health. This thesis is comprised of two studies. Study 1 examines how naturally-occurring population-level PA interventions with children have been evaluated in previous studies by conducting a systematic review. A total of 15 papers were included for review and results suggest that naturally-occurring population-based PA interventions are generally effective in improving PA levels of children in a variety of PA domains. Eleven studies included additional evaluation components to help justify results and provide important contextual information. Using an ecological framework, Study 2 investigates how the provision of a naturally-occurring population-based PA intervention in London, Ontario impacted children’s PA levels. A total of 643 children completed baseline and post-intervention surveys. Results showed a significant increase in PA over time, with significant increases for girls, visible minorities, children born outside of Canada, children with low parental support, and children from all neighbourhood SES groups. Sex and parental support were the only significant predictors of change in PA. Examining naturally-occurring population-based PA interventions is a beneficial opportunity that should be used by researchers to provide real-world evidence of effective strategies to assess and increase children’s levels of PA
