Editors' Summary: In this Article, William W. Wade evaluates the conceptual measurement of economic impact within the Penn Central test for income-producing properties recently adjudicated in the U.S. Court of Federal Claims and U.S. Court of Appeals for the Federal Circuit. The discussion considers measurement of the denominator of the takings fraction related to Penn Central's parcel as a whole and whether it differs between permanent and temporary takings. He concludes that the Federal Circuit's recent decision to rely on change in value appraisal methods upsets a strong line of precedent that relied on the more appropriate return on equity approach.