Walking for transportation is part of an active lifestyle that is associated with decreased risks for heart disease, diabetes, hypertension, and colon cancer and an increased sense of well being. However, the percentage of trips made by walking has declined over time among both children and adults. One of the objectives of Healthy People 2010 (no. 22-14b) is to increase among children and adolescents the proportion of trips to school made by walking from 31% to 50%. In 1969, approximately half of all schoolchildren walked or bicycled to or from school, and 87% of those living within 1 mile of school walked or bicycled. Today, fewer than 15% of children and adolescents use active modes of transportation. This report examines data from the 2004 ConsumerStyles Survey and a follow-up recontact survey to describe what parents report as barriers to their children aged 5-18 years walking to or from school. Distance to school was the most commonly reported barrier, followed by traffic-related danger. Comprehensive initiatives that include behavioral, environmental, and policy strategies are needed to address these barriers to increase the percentage of children who walk to school.