We propose in this competing continuation to extend our current project examining the association between physical activity and obesity within ALSPAC by repeating the objective physical activity measures at age 15. These extended measurements will allow us to further explore the associations between physical activity, obesity and CVD risk factors prospectively in this large contemporary population-based study of children.The 15-year clinic has started (October 2006) and we are managing to collect collecting data during this interim period using our existing resources from the original grant (staff, equipment, etc). If we are unsuccessful with the renewal application we will cease measurements when the current grant ends (May 2007).