The restoration of the Everglades provides a case in point (Central and South Florida Project 1999). The demand for prediction of restoration success has outstripped scientific knowledge (Zedler 2000). Just measuring the expected costs and benefits of wetland protection is difficult. Yet, even if expected costs and benefits could be calculated, there is additional option value to avoiding irreversible loss of wetlands. While the theory of option values is well understood, estimating the size of such option values is relatively uncharted territory.