Conceptual and empirical examination of whether the social costs imposed by hazardous waste sites are reflected in property values. A hedonic analysis is used, to account for other characteristics of houses that affect their values. After screening many sites, data are collected and analyzed for two of them. For the Andover site, where contamination was detected in on-site wells but not in wells outside the site boundaries, there was no evidence of an effect on property values. For Pleasant Plains, where contaminated wells had to be closed, there was some indication of expected rent gradient. Further analysis is reported in Volume II.