In the past, active transportation to school offered an important source of daily physical activity for youth; more recently, however, factors related to distance, safety, or physical or social environments may have contributed to the proportion of children who travel to school by motorized vehicle. The authors examine the characteristics of children who use active transportation to school (ATS) as an important first step in developing effective strategies for intervention. No national study, however, has elucidated the characteristics of youth who use ATS. The present study uses a national sample of boys and girls in grades 4-12. A computer-assisted telephone interview is conducted from 1,458 parent-child pairs residing in the U.S. The interviewers asked each parent and a randomly selected child from the same household about patterns of physical activity and characteristics thought to predict such activity. Significant characteristics (p< .05) from univariate logistic regression analyses were included in multivariate logistic regression analyses using SAS (version 8.2; SAS Institute, Cary, NC). Overall, 14% of children and adolescents reported ATS. ATS was more frequent among boys (16.6%) than girls (11.1%), and among children in lower than upper grades: 20.5% in grades 4-6 and 12.4% in grades 7-9 versus 8.0% in grades 10-12. The cross-sectional analysis suggests that having sidewalks is an important element of a child's environment to promote ATS. The analysis also indicates that girls and students in the highest grades (10-12) need assistance to increase ATS.