Emerging evidence supports a link between neighbourhood built environment and physical activity. Systematic methodologies for characterising neighbourhood built environment are needed that take advantage of available population information such as census-level demographics. Based on transportation and urban planning literatures, an integrated index for operationalising walkability using parcel-level information is proposed. Validity of the walkability index is examined through travel surveys among areas examined in the Neighborhood Quality of Life Study (NQLS), a study investigating built environment correlates of adults' physical activity.