16 The Brookings Review Summer 1985 CR I T I C S of the American political system have repeatedly charged that its fragmentation of power makes it incapable of governing a modern society. The constitutional system of checks and balances and a weak party system, it is alleged, prevent the federal government from making decisive and rapid policy choices ? and complicate the implementation of those choices once they are arrived at (or muddled to). The results are said to be incrementalism or stalemate, leading to poor performance in such crucial areas as economic growth and the reduction of energy dependence.1 The British parliamentary model is often adduced as both inspiration and exemplar for reforms in this country.2 But do parliamentary systems actually perform better than the American one? While separating out the variables that contribute to differing policy outcomes across nations is a notoriously difficult task,3 this article will suggest that the answer to the foregoing question is likely to be negative. The point to be made is that there is a large gap between the the oretical potential of parliamentary systems and their actual performance. This essay outlines reasons for this gap, drawing upon evidence from the two parlia mentary nations that are culturally most similar to the United States: Great Bri tain and Canada.