Federal tax law has long provided a tax benefit for charitable contributions of easements for conservation purposes.  This Article argues that a fundamental problem with this conservation easement tax expenditure is that the measure for the tax benefit—lost economic development value—is erroneous.  The Article explains that the easement program is reflexively justified and understood based on this false measure, as if it represented the conservation value of the program, and that use of such an erroneous measure obscures the conservation benefits of the program by focusing attention and resources on divining a largely extraneous and unhelpful number.  The Article argues that, in theory, the measure for the tax benefit should be changed to one that better approximates conservation value.  This would help ensure that the program is efficient, in the sense that conservation benefits would exceed program costs.  However, conservation value is not, at least not yet, readily susceptible to quantification for tax purposes.  Accordingly, this Article suggests a second-best approach:  changing the measure of the tax benefit to a more objective number—the fair market value of the underlying fee interest—to provide greater certainty and to shift administrative and legal resources and attention to the conservation benefits of the program.  The Article provides several additional suggestions for reforming the easement program, and concludes that, regardless of the details, the conservation easement tax expenditure should be designed to promote a concept of conservation value—an affirmative value—that should represent the highest and best use of the land.