Given limited funding for Safe Routes to School (SRTS) programs in the US, there is great need for practitioners to understand how interventions affect walking and biking and to identify effective low-cost strategies. A pilot program at the Eugene 4-J school district in Oregon provided a unique opportunity to evaluate the effectiveness of infrastructure and encouragement programs using a natural experiment. The purpose of this study was to evaluate three SRTS interventions - Walk to School Day, built environment infrastructure improvements, and Freiker (a bike-specific encouragement program) - which were implemented in Eugene in 2008-2009. Rapid-response funding was awarded to collect data on student travel after implementation and to analyze the effectiveness of each intervention before the SRTS program ended in late 2010. The proportion of children at each school that walk and bike was measured using the National Center for SRTS's parent and classroom survey forms. Cost of each intervention was also evaluated.