Much has been written about the putative virtues and vices of federal and unitary systems of government, but little empirical testing of the impact of such systems on the quality of governance has been conducted. Do federal or unitary systems promote better social, political and economic outcomes? The paper takes up a series of theoretical debates put forth by advocates of federalism, including competition among subnational governments, fiscal federalism, veto points, accountability, and the size of government. In each case, there is room for doubt about the practical impact of federalism on governance. The paper then conducts a series of cross-national empirical tests over several decades of the impact of unitary systems on fifteen indicators of political, economic and human development. In most cases, a strong empirical relationship between unitarism and good governance obtains. To the extent that these constitutional structures make a difference, unitary systems appear to hold distinct advantages over federal ones.
