The last twenty-five years of the twentieth century were freighted with important moments for historians of economic thought: the collapse of the Keynesian consensus, the rise (and fall) of monetarism, the collapse of the former Soviet Union and the other Marxist-Leninist states in central and eastern Europe, the rise of neo-liberalism, and arguments over the possible emergence of a “New Economy” following the internet investment boom at the end of the 1990s. Each of these moments will require its own history as we slowly move away from the tumult of the times and begin to weigh them for their own significance. But several of the moments have a common iconic face in Margaret Thatcher, the Prime Minister of Great Britain from 1979 to 1990. Few other individuals so readily embody the sense of the times. Thatcher's election—a full year and a half before Ronald Reagan's—marks for many people the moment when Keynesian policies finally and irretrievably lost their legitimacy. Likewise, the timing of her election, just two months before Paul Volcker's selection as the chair of the Federal Reserve Board of Governors in the United States, also means that for many people Thatcher's is the public face of monetarism's ascendancy. Finally, there is probably no one person whose name is so clearly associated with the rise of free market thinking and neo-liberalism during the end of the twentieth century.