Abstract: Childhood obesity has doubled in the last thirty years. At the same time, youth travel patterns have changed greatly. In 1969 42% of students walked or biked to school; now 13% do. These two trends have caught the attention of policymakers who have identified walking to school as a way to reintroduce physical activity into children's lives. However, these policies have been made without much knowledge of children's travel—an area which has been understudied by transportation researchers. This dissertation seeks to fill this knowledge gap and provide information to design better policies by asking three questions: (1) What are the current patterns of children's travel? (2) What factors have the greatest influence on children's mode choice for school trips, particularly for walk trips? and (3) How can land use planning affect walking to school? All analyses identify the spatial distribution of students and schools as the primary reason for the low rates of walking to school. For example, in 1969 45% of elementary school students lived less than a mile from their school; today fewer than 24% live within this distance. The simple fact is that most children do not live within a walkable distance of their schools. When children do live close to school, substantial numbers walk. However, current policies aimed at increasing walking to school focus on improving trip safety rather than changing distance to school. To encourage large numbers of children to walk to school, planners will need to coordinate land use and school planning. Including children's distance from school as a planning criterion could be an effective way to change community design and encourage walking. This coordination is most necessary in moderate and high density areas where neighborhood schools are a possibility. However, even in low-density areas, planners can optimize school and housing placement so that a large portion of students live within a walkable distance of their school.