There he studied under Sheldon Wolin, John Schaar and Norman Jacobson, and also recognized the influences of political theorists Leo Strauss and Bertrand de Jouvenel.
He was also active in the early stages of the Berkeley Free Speech Movement and the student activist group SLATE.
At Harvard he taught the evening seminar "American Political Theory in the 19th Century" during the spring of 1998, a popular course attended by several professors including Harvey Mansfield.
[citation needed] McWilliams was author of The Idea of Fraternity in America (1973, University of California Press), for which he won the National Historical Society prize in 1974.
He argued that this tradition drew philosophical inspiration from ancient Greek and Christian sources manifested in an emphasis upon community and fraternity, which was properly the means to achieving a form of civic liberty.