US children's active commuting to school (ACS; walking or cycling to school), previously common (48% in 1969) is now uncommon (13% in 2009). This decline coincided with the obesity epidemic, which disproportionately affects low-income and ethnic minority children. Programs to increase children's moderate-to-vigorous physical activity (MVPA) and lower obesity and related chronic disease risk are necessary. The Bicycle Train is an innovative program in which children cycle to and from school led by adults. Bicycle Trains provide another option for ACS, especially for children who live too far to walk to school. No randomized controlled trials (RCT) have evaluated Bicycle Trains and children's ACS or MVPA. Increasing the percent of children who cycle to school is sub-objective PA-14 of US Healthy People 2020.