In this paper, we focus on the relationships between international accounting harmonization (IAH) and the paradigm of Fair Value Accounting (FVA). Accountants rely on the accounting concept of comparability in defining IAH and are in agreement that a set of internationally implemented Generally Accepted Accounting Principles (GAAP) is required for a "complete harmonization." We argue, however, that a second requirement4 common denominator for measuring, recording, and reporting business transactions, assets, liabilities, and equitieH's necessary to reach a state of a "complete IAH." We explain the logic behind the requirement of a common denominator and assert that I A H is feasible under the paradigm of FVA, but not under that of Historical Cost Accounting (HCA). This is true because the concept of fair value, but not historical cost, provides the common denominator necessary for a meaningful comparison of accounting data. We then argue that the paradigm of FVA acts as a catalyst in a harmonization cycle: FVA propels I A H and IAH provides more relevant information that may foster the eficiency of global markets, which improves the quality of the FVA figures. The authors acknowledge the helpful and constructive comments of an annonimous referee. Professor Barlev acknowledges financial support from the Krueger Center for Finance and the Accounting Center at the Hebrew University of Jerusalem, Israel.