This study was conducted to determine if fifth-grade students who walked or bicycled to school on a regular basis were more physically active than those that did not. The sample consists of 219 fifth-grade students (10.3 +/- 0.6 yr, 44% male, 58% minority) from eight randomly selected urban and suburban elementary schools. Students wore an Acti-Graph physical activity monitor during the same week that they completed a daily survey to report their mode of transportation to and from school. Students were categorized on the number of reported active commuting trips, to and from school, per week (regular;>or=5 (N=11), irregular; 1-4 (N=25), nonactive; 0 (N=183)). Compared with both other groups, regular active commuters accumulated 3% more minutes of moderate-to-vigorous physical activity (MVPA; P=0.04) during weekdays. This weekday difference was because of regular active commuters accumulating 8.5% more minutes of MVPA both before and after school (P <or= 0.01). No difference in physical activity was seen among groups during school or in the evening. Based on the mean number of minutes the students wore their monitors on weekdays (800 min.d), the 3% difference translates into approximately 24 additional minutes of MVPA per day for the regular active commuters. Walking to school was associated with approximately 24 additional minutes of MVPA per day in fifth-grade students. Additional observational and experimental research in larger, more diverse samples is needed to further clarify the effects of active commuting to school on total daily physical activity and other health outcomes.