A growing body of evidence documents multiple ways in which land use and transportation investments influence health. To date, most evidence linking the built environment to health either focuses on behavioral change or environmental exposures. Few studies simultaneously assess how behavior and exposure-based impacts of the built environment interact. This is concerning as increased walkability and transit access can possibly lead to increased exposure to air pollution and injury risk. This paper synthesizes recent research on behavior and exposure-based mechanisms that connect land use and transportation investments with various health outcomes. Exploring the nexus between these pathways provides a framework to identify priority areas for research to inform policies and investments. The most studied pathway articulates how land use and transportation can support healthy behaviors, such as increased physical activity , healthy diet, and social interactions. The second pathway articulates exposure to harmful substances and stressors and potential differential impacts by travel modes. Increased rates of active travel lead to lower generation of vehicle emissions and kilometers traveled; but may actually result in increased exposure which may have adverse effects on sensitive populations such as elderly and youth. Unhealthy exposures have historically concentrated in areas where the most disadvantaged reside – along major transportation corridors where land is cheapest and more affordable housing is located. A high priority for future research is to examine mechanisms that spatially link built environment and chronic disease . More longitudinal evidence is required inclusive of biomarker data within clinical trials to isolate independent and interactive effects of biological and neurological mechanisms from behavioral and exposure related impacts of the environment. Downstream impacts of the built environment on healthcare utilization and costs and workforce productivity is needed for policy makers to justify the ma...