To offer some concrete answers to this question, this paper reports the findings of a synthesis of cross-country empirical work on the ranking (in terms of efficiency and distributional impact) of major tax instruments on the one hand, and, on the other, country-specific tax policy assessments reported in several dozen OECD Economic Surveys since 2008. The paper identifies a wide range of factors, some common to many countries and some country-specific, that prevent governments from adopting tax structures more favourable to inclusive growth. These include political economy forces, legal obstacles, administrative constraints, and intergovernmental fiscal arrangements.