Background: Increasing physical activity in youth is a recommended approach to curbing the childhood obesity epidemic. One way to help increase children's daily activity is to promote active transportation to and from school (ATS). Purpose: The purpose of this case study was to explore parental perception of, and participation in, ATS initiatives. Methods: This study is part of a larger project on ATS initiatives conducted by the Physical Activity Policy Research Network. Sixty-nine key informants, including 10 parents, were interviewed at nine diverse elementary schools being studied for their ATS policies. A standard interview guide was used. The interviews were audio-recorded, transcribed, and analyzed. Results: Analysis revealed that parental support was a necessary component for ATS success. The parents' roles varied greatly. Most parents chose to become involved in ATS for a specific reason (e.g., promoting health). The parents and other key informants interviewed expressed participation benefits such as promoting healthy behaviors, increasing social opportunities, promoting neighborhood awareness, and fostering community improvement. Barriers to participation included lack of time, language barriers, and preference for auto travel. Parents also had safety concerns about ATS. Discussion: Parents can be valuable resources in school ATS programs, as noted by parents and key informants. Their level of involvement can vary from coordinating a program to leading a walking group; whatever the case, parental participation facilitates a successful initiative. Translation to Health Education Practice: ATS initiatives provide a way for parents to become involved in a school program that has personal health, social, and community benefits. (Contains 2 tables.)