BACKGROUND: The Robert Wood Johnson Foundation (RWJF) provided Columbia MO with an Active Living by Design (ALbD) grant in 2003 to promote active living in the community. A separate project was funded in 2006 through RWJF's Active Living Research program. PURPOSE: To evaluate whether participation in a Walking School Bus (WSB) program increased or decreased active living in elementary school children residing in Columbia, in association with ALbD funding. METHODS: Objective measures of physical activity obtained using accelerometers were collected over 7 days in children participating in a WSB program and children in a nonparticipating comparison group. Differences in the percentage of time spent in moderate- to vigorous-intensity exercise (%MVPA) were compared between groups. RESULTS: Children in WSB programs showed no differences in %MVPA compared to children not participating in the WSB; however, when comparing the relationship of %MVPA and age, the slope of the regression line was steeper for those children not participating in the WSB. CONCLUSIONS: The ALbD intervention in Columbia did not result in measurable changes in physical activity in children participating in the Walking School Bus program, but there was a negative association between age and physical activity, and the slope of that regression line was affected by participation in the program.