Focusing on the period of Milton Friedman's collaboration with Anna J. Schwartz, from 1948 to 1991, this work examines the history of debates between Friedman and his critics over money's causal role in business cycles. Professor Hammond shows that critics' reactions were grounded in two distinctive features of Friedman and Schwartz's way of doing economic analysis—their National Bureau business cycle methods and Friedman's Marshallian methodology. Drawing extensively on unpublished materials, Professor Hammond's treatment offers new insights on Milton Friedman's attempts to settle debates with his critics and his eventual recognition of the methodological impediments.