This paper attempts to measure systematically the extent of blight in a single metropolitan area. Using a sample of individual dwelling units, the paper first describes a method of quantifying some previously neglected aspects of residential quality and demonstrates that they are highly valued by urban households. Secondly, it illustrates the feasibility of generalizing these quality measurements of sample dwellings to all city blocks using widely available explanatory variables. The analysis finds strong inferential evidence of an important, but elusive, relationship among the level of public services provided to particular dwelling units (police protection and schools), measures of residential quality, and the market's valuation of these units. The models described in this paper relate to an important range of urban renewal questions. For example, they can be used to obtain lower bound estimates of the potential benefits of urban renewal programs.