Research on physical activity and the physical environment is at the correlates stage, so it is premature to attribute causal effects. This paper provides a conceptual approach to understanding how the physical design of neighborhoods may influence behavior by disentangling the potential effects of income, university education, poverty, and degree of urbanization on the relationship between walking to work and neighborhood design characteristics. The study merges Canadian data from 27 neighborhood observations with information on walking to work from the 1996 census. Hierarchical linear modeling was used to create a latent environment score based on 18 neighborhood characteristics (e.g., variety of destinations, visual aesthetics, and traffic). The relationship between the environment score and walking to work was modeled at the second level, controlling for income, university education, poverty, and degree of urbanization. With the exceptions of visual interest and aesthetics, each neighborhood characteristic contributed significantly to the environment score. The environment score was positively associated with walking to work, both with and without adjustment for degree of urbanization. Controlling for university education, income, and poverty did not influence these relationships. The positive association between the environment score and walking to work, controlling for degree of urbanization supports the current movement toward the development of integrated communities for housing, shops, workplaces, schools, and public spaces. Given the need for research to guide environmental interventions, collaboration among public health practitioners, urban planners, and transportation researchers is essential to integrate knowledge across sectors.