摘要:Background. Adolescent girls are less likely to meet physical activity recommendations than boys. This study examined the relative contribution of structured physical activity opportunities including physical education (PE) class and sports teams to overall activity levels for girls and boys. Methods. Data from 591 9th–12th grade students who completed the 2009 Philadelphia Youth Risk Behavior Survey were examined. Logistic regression was used to estimate the relationship between PE and sports teams and physical activity levels. Models were stratified by gender to estimate gender differences. Results. Girls were less likely to be active than boys: 27.9% of girls were sedentary as compared to 10.6% of boys. PE class was not related to activity levels among boys, while highly active girls were seven times more likely to participate in daily PE than were sedentary girls. Playing on one or more sports teams was associated with low-moderate and high activity in girls; among boys, sports team participation was only associated with high activity. Conclusions. The structured physical activity opportunities of PE and sports teams may contribute more to overall activity levels in girls than boys. A more rigorous assessment of this hypothesis is warranted to inform efforts to promote activity levels in girls.