This research examines the use of individualized marketing as a transportation demand management (TDM) strategy, using the City of PortlandÕs SmartTrips program. This research has two specific aims: (1) to evaluate whether the benefits of these individualized marketing programs continue to at least one year after the project ends; and (2) to examine whether the theory of planned behavior (TPB) can help explain the behavior changes identified. Surveys of residents conducted one or two years after the original program found that the share of daily trips made driving alone, walking, and bicycling were comparable to that found in the previous follow-up surveys.