Abstract: Although similarities between the British and American systems of financial regulation are often remarked upon in academic commentary, the organizational structure of financial supervision in the two countries has diverged substantially in the past decade, as the United Kingdom has now largely consolidated its financial regulatory agencies in the Financial Services Authority whereas the United States has maintained the world's most decentralized and fragmented collection of financial supervisory agencies. In this essay, Professor Howell Jackson explores various reasons why financial regulation in these two countries differs so dramatically in organizational structure. Focusing first on the differences in political economy that surrounded the enactment of the Financial Services and Markets Act of 2000 in the United Kingdom and the Gramm-Leach-Bliley Act of 1999 in the United States, Professor Jackson discusses deeper differences in the regulatory philosophies of the two countries and also presents data on the relative intensity of financial regulation in both jurisdictions. He speculates that the comparatively more ambitious regulatory agenda of the U.S. system pushes the country towards a more elaborate system of financial oversight that is inherently more difficult to consolidate. In the United Kingdom, in contrast, the goals of the financial regulators are more modest and, to the extent that cost efficiency is one of the country's regulatory objectives in the field of financial regulation, that policy tends to foster a less cumbersome system of financial regulation that more easily accommodates consolidation of regulatory functions. The paper concludes with some broader comparative data suggesting that while British financial regulation may be less intensive than financial regulation in the United States, it is substantially more intensive than financial regulation in many other jurisdictions, particularly civil law jurisdictions on the Continent.