This document describes a study that developed a method using Geographic Information Systems (GIS) to characterize obesogenic urban environments by integrating measures of the food and physical activity environments. The study designed a multivariate tool to assess these environments in median neighborhoods of around 15,000 residents in an urban area. The tool used kernel density estimation to calculate a synthetic index from factors representing availability and access to food and opportunities for physical activity. The index was intended to help inform future urban health interventions and research by identifying neighborhoods that may promote or hinder healthy behaviors.