Public health researchers have identified numerous health implications associated with land use. However, it is unclear which of multiple methods of data collection most accurately captures land use, and “gold standard” methods vary by discipline. Five desirable features of environmental data sources are presented and discussed (cost, coverage, availability, construct validity, and accuracy). Potential accuracy issues are discussed by using Kappa statistics to evaluate the level of agreement between data sets collected by two methods (systematic social observation [SSO] by trained raters and publicly available data from aerial photography coded using administrative records) from the same blocks in Chicago, Illinois. Significant Kappa statistics range from 0.19 to 0.60, indicating varying levels of intersource agreement. Most land uses are more likely to be reported by researcher-designed direct observation than in the publicly available data derived from aerial photography. However, when cost, coverage, and availability outweigh a marginal improvement in accuracy and flexibility in land-use categorization, coded aerial photography data may be a useful data source for health researchers. Greater interdisciplinary and interorganization collaboration in the production of ecological data is recommended to improve cost, coverage, availability, and accuracy, with implications for construct validity.