BACKGROUND: Most studies of active travel to school (ATS) have been conducted in urban or suburban areas and focused on young children. Little is known about ATS among rural adolescents. PURPOSE: To describe adolescent ATS in two predominantly rural states and determine if school neighborhood built environment characteristics (BECs) predict ATS after adjusting for school and individual characteristics. METHODS: Sixteen BECs were assessed through census data and onsite observations of 45 school neighborhoods in 2007. ATS and individual characteristics were assessed through telephone surveys with 1552 adolescents and their parents between 2007 and 2008. Active travelers were defined as those who walked/cycled to/from school >/=1 day/week. Hierarchic linear modeling was used for analysis, conducted in 2009. RESULTS: Slightly less than half (n=735) of the sample lived within 3 miles of school, of whom 388 (52.8%) were active travelers. ATS frequency varied by season, ranging from a mean of 1.7 (SD=2.0) days/week in the winter to 3.7 (SD=1.6) in the spring. Adolescents who attended schools in highly dense residential neighborhoods with sidewalks were most likely to be active travelers. ATS frequency was greater in school neighborhoods with high residential and intersection densities, on-street parking, food outlets, and taller and continuous buildings with small setbacks. CONCLUSIONS: The BECs that support safe travel may be necessary to allow for ATS, whereas ATS frequency among adolescents may be influenced by a wider variety of design characteristics. Additional strategies to promote ATS and physical activity are needed in rural areas because of long commuting distances for many students.