Alternative measurement bases or assets and liabilities have different implications for the information reflected in comprehensive income. Thus, the development of measurement concepts also needs to consider whether comprehensive income based on a particular measurement base is more or less useful to financial statement users than another. The discussion raises several other open issues that need to be considered, including how best to display the information embedded in any particular measurement and whether , why, and how measurement should differ for financing and investing and for nonfinancial prating activities. Because measurement in financial reporting is so fundamental, some might be afraid of the answer that follows from a serious effort at developing soung measurement concepts. In particular, opponents of fair value might be concerned that the development effort might confirm the assessment in this paper that fair value fits with the existing Framework concepts better than unmodified or modified historical cost. However, there are many unresolved issues and measurement in financial reporting is too fundamental to proceed without concepts. Simply crafting concepts to justify current practice is inappropriate. Concepts need to be just that, concepts. Once the concepts are developed, the next challenge is to follow them.