With an increased focus on reducing the effects of motor vehicle use on the environment, neighborhood livability, safety, and health, planners, engineers, and policy makers are looking to increase the attractiveness of walking and bicycling. The potential for bicycling as a transportation mode has been recognized nationally through objectives to raise bicycling rates (FHWA, 1999) and significant increases in funding for building new infrastructure (FHWA, 2002). Several states and cities have also adopted aggressive policies and programs to increase bicycling (League of American Bicyclists, 2008). The City of Portland, already arguably the best large US city for bicycling, recently adopted a Bicycle Plan that aims to achieve a 25% mode share by 2030, with a key principle of attracting new riders through expanding the network of "low stress" facilities that minimize interactions with motor vehicles. The main type of low-stress facility the City plans on expanding significantly are "bicycle boulevards," a form of traffic calming on residential streets that give bicycles priority over motor vehicles. Despite an increasing focus on bicycling for transportation, there is a lack of good research to help guide policy making. A recent review of 139 studies from the U.S. and abroad of the effects of various programs, policies, and infrastructure on levels of bicycling often found positive relationships but also identified many gaps in the research and methodologies employed (Pucher, Dill, & Handy, 2010). The crucial limitation, however, is that most studies fall far short of the ideal research design for evaluating interventions, involving before-and-after measurements of a "treatment" and a "control" group (Krizek et al., 2009). The decision to bicycle for transportation involves a wide range of factors. Recognizing this complex system, researchers have developed ecological models to help guide our work (Sallis et al. 2006, Pikora et al. 2003, Saelens, Sallis and Frank 2003). Ecological models assert that both individual and physical environmental factors influence walking and bicycling behavior for recreation and transportation. Individual factors can include demographics, attitudes towards walking/cycling, perceived behavioral control, and social factors and norms. Physical environmental factors can include such things as access to bicycle lanes and other infrastructure, the quality of that infrastructure, hills and weather, land uses, traffic, and aesthetics. While these models can be very enlightening and are a useful framework for researchers, their level of complexity make them less useful to practitioners. Instead, the City of Portland has used a typology of cyclists to guide its planning efforts, placing residents into one of four groups: Strong and the Fearless; Enthused and the Confident; Interested but Concerned; and No Way No How. They estimate that the first two categories make up less than 8% of the population and account for most of Portland's current success as a cycling city. On the other hand, they think that about 60% of the population are "Interested but Concerned" and that these residents are the key to increasing mode share significantly. The City developed this typology using a number of secondary data sources and feedback from expert practitioners, but has not conducted research to validate the categories, understand who exactly falls into each category, and what that means for predicting future demand for cycling given the City's adopted strategy. This research project has two primary objectives: (1) Validate (or expand on) and better understand the "Four Types of Cyclists" typology developed by the City of Portland; and (2) Evaluate the effects of new, innovative infrastructure (bicycle boulevards) on the levels of bicycling, physical activity, and health among the four (or more) types of cyclists. The first objective will be addressed through a random phone survey of adults in the Portland region. The second objective will be addressed with a longitudinal panel study of families living near bicycle boulevards that will be constructed in the next year. Family members will be asked to carry a GPS and accelerometer with them for up to one week to measure their physical activity, including bicycling and walking. They will also complete surveys to collect data on attitudes and behaviors, including how they fit into the cyclist typology. We will collect data before and after the boulevards are built, approximately one year apart, from the same families. The study areas will include two neighborhoods with new bicycle boulevards (but little other existed bicycle infrastructure) and two control neighborhoods.