Background <p>People with intellectual and developmental disabilities (IDD) face persistent barriers to physical activity, and past interventions have mainly targeted individual behaviors, often with limited reach and short-term success. Built environment approaches—such as improved pedestrian, bicycle, and public transportation infrastructure—can help remove barriers by providing safe, accessible routes to essential destinations. This study’s aim was to understand active transportation practices and preferences among people with IDD, with a goal of informing more inclusive built environment approaches.</p> Methods <p>The study employed a qualitative design informed by a Project Advisory Board including people with IDD and staff. Inclusive methods were used to meaningfully and appropriately engage people with IDD throughout the study, including adapted materials, processes, and interview techniques. Multi-site and snowball sampling was used to recruit adult Special Olympics athletes. Virtual semi-structured interviews were conducted using a guide based on active transportations mode (walking or rolling, biking, public transit) and evidence-based built environment approaches. Results were analyzed through a rapid deductive approach with a coding matrix aligned with the interview guide. Saturation (presence of unique barriers) was calculated and met.</p> Results <p>Participants (<i>n</i> = 12) reported using both active and inactive transportation modes. Walking was the most common form of active transportation, yet most interviewees described barriers including inaccessible or nonexistent sidewalks, poor weather, and a lack of connected routes to nearby destinations. Public transportation was facilitated by frequent stops near everyday destinations but could be inconvenient with limited service. Most athletes did not bicycle due to coordination or balance challenges. Drivers not paying attention impeded both bicycling and walking. Some interviewees also reported using micromobility options (e.g., golf carts) for transportation.</p> Conclusions <p>Built environment approaches and comprehensive transportation systems could improve active transportation opportunities for people with IDD. This includes both approaches specific to those with IDD (e.g., adaptive micromobility options) and universal design approaches (e.g., wider sidewalks) that could improve safety, comfort, and convenience for all community members. Future work should include testing the innovative strategies identified here to understand impacts on physical activity levels, independence, and quality of life for people with IDD.</p>