Advances in behavioural economics have begun to provide a new toolkit of theories, models, and empirical methods for designing and evaluating policy. While many of these techniques are highly relevant to behavioral problems that planners encounter when consulting the public, crafting policy and regulations, and promoting sustainable patterns of behavior, this approach has received only limited attention in the planning and transportation literature. I review this literature and present a framework for generating, implementing, and testing the results of different interventions designed to affect users’ travel behavior by delivering behavioral feedback via an activity-tracking smartphone application. The results of this promotional strategy are tested in two pilot projects among university students and “Bike to Work Week” participants in British Columbia and Minnesota. I also present further tools for conducting such experiments and additional experimental designs relevant to testing these hypotheses. Implications for program evaluation, planning practice, and transportation research are discussed.