This paper provides a reconstruction of the intellectual cross-fertilization between Adolf Berle and John Kenneth Galbraith to account for their institutionalist challenge against “conventional economics” so as to bring political economy back to life. To do so, I go back to the genesis of Modern Corporation and Private Property before analyzing Berle and Galbraith’s answers to a set of fundamentals questions. What is the nature of modern competition ? What is the nature of the modern corporation ? What is the role of the State ? Lastly, how should American liberalism be reinvented to cope with the social issues of an affluent society ? Their answers to these questions reveal the deep affinities between the theoretical and political dimensions of their works, so that this work lies at the crossroads of the history of economic thought and the history of American liberalism in the postwar period.