The structure and purpose of this paper reflect both its origins and my limitations. As part of a broader study of “Taxation for Effective Governance and Shared Growth” being carried out for the U.K. Department for International Development (DFID), I was asked to prepare a background paper from a tax perspective. The project as a whole was intended to link macroeconomic modeling to the challenges facing developing countries with respect to tax effort, political accountability and sustainable economic growth. The terms of reference asked authors to present the latest evidence and best knowledge in their areas, to evaluate the findings and suggest both detailed policy options and areas for improved research as well as “practical operational guidance” for the international community and partner governments. In the tax paper, I was asked to consider challenges with respect to tax policy and administration in meeting the domestic revenue mobilization objectives of the Monterrey Consensus,with specific reference to how to achieve politically and administrative sustainable pro-growth revenue collection without unduly burdening the formal economy - for instance, through more effective and transparent administration and broadening the tax base. The challenge thus set is formidable. This paper is my attempt to meet it. Inevitably, it falls short in some respects, notably when it comes to providing ‘practical operational guidance’ for the international community. This lapse is not accidental. Developing countries, like the rest of the world, exist in a complex and changing international environment, and tax outcomes in many of them have been affected, sometimes adversely, by globalization. My focus here, however, is not on what the world has done to, or should do for, developing countries but rather on what countries should and can do to help themselves, irrespective of how the world treats them. Throughout the paper I suggest many ways in which countries can, if they wish, improve their tax systems in terms of structure, administration, and (at least from my perspective) outcomes. In the course of doing so, I attempt to respond to all the points noted above as best as my reading of the evidence and my own experience enable me to do. In the end, however, I do not suggest many ways in which the rest of the world can intervene and directly help developing countries to improve their tax systems. I do not do so primarily because, as I explain in the paper, one of the most important lessons from the half-century or more that fiscal experts have been in the ‘tax advisory’ business is that one cannot sell good tax policy or administration to those who are unwilling to buy them. If the international community wants developing countries to do more to meet fiscal challenges, its main contribution, I suggest, should be to improve the capacity of the domestic policy communities in those countries to cope with such challenges in their own way, not to tell them in detail how they should do it.