Active commuting to school has health implications among young people. We aimed to (a) examine the patterns of commuting to school in children and adolescents regarding gender and area of residence, (b) study the association between distance from home to school and mode of commuting, and (c) identify the threshold distance below which young people are more likely to walk to school. A total of 6,004 students aged 7 to 18 years from Spain participated in this study. Mode of commuting was self-reported and distance was objectively measured using Google Maps software. Associations were examined using binary logistic regression and receiver operating characteristic curves analysis. Around 67% of children and 60% of adolescents commuted to school actively (mainly walking). The threshold distance for walking to school was 875 m, 0.54 miles, in children, and it was higher among urban (1,250 m, 0.78 miles) than in rural participants (675 m, 0.42 miles). The threshold distance for walking to school was 1,350 m, 0.84 miles, in adolescents, and it was lower among urban (1,350 m, 0.84 miles) than in rural participants (1,550 m, 0.96 miles). Future interventions on active commuting to school should consider this threshold distance, and chances of promoting an active commuting to school could have as a goal the increase of this threshold distance.