Throgmorton has argued that survey results are tropes, or rhetorical devices, that establish a context for the frankly political debates that occur within planning processes. Planners responsible for the economic evaluation of plans and projects increasingly are using a particular type of survey, the contingent valuation (CV) survey, to estimate the value of public goods such as water quality and recreation. It is argued in this article that CV is a useful tool for planning and that, following Throgmorton, planners will be more effective if they accept the idea that the results of CV surveys are both scientific and contestable. In this study, the CV-type questions about willingness to pay provided information not available from conventional surveys and helped local decision makers gauge the strength of local support for a parks board. Effective use of CV, like use of other survey data, requires that planners be competent technically and politically.