This paper examines the question of tax reform in OECD countries. First, the reasons for tax reform are reviewed. These include economic efficiency arguments as well as concerns about equity which are often a major consideration. Next, the paper considers the many factors which constrain governments in their effort to reform the tax system (such as inherent conflicts between efficiency and equity, and the non-revenue objectives of taxation), and how those constraints might be reduced. Finally, the paper reviews the extent of tax reform in OECD countries, noting some of the remaining problems ...