Safe Routes to School (SR2S) programs attempt to promote safe walking and biking to school. Previous interventions have mainly focused on route characteristics of sidewalks and bike paths, omitting the walkability of the areas around schools and the potential impact of urban trails. The purpose of this dissertation was to develop a School Buffer Walkability Index (SBWI) tool to integrate objective and subjective measures of schools’ aerial buffers and to test the association of the SBWI and children’s walking to school. Comparisons were made between school minority (non-white) and white elementary school kids in Austin, TX for their SBWI and levels of walking to school. Variables included in the SBWI were land use mix, residential density, street connectivity, sidewalks and bike paths, traffic and crime safety, and trails.