One of the most significant industrial states in the country, with a powerful radical tradition, Pennsylvania was, by the early 1950s, the scene of some of the fiercest anti-Communist activism in the United States. Philip Jenkins examines the political and social impact of the Cold War across the state, tracing the Red Scare's reverberations in party politics, the labor movement, ethnic organizations, schools and universities, and religious organizations.

Among Jenkins's most provocative findings is the revelation that, although their absolute numbers were not large, Communists were very well positioned in crucial Pennsylvania regions and constituencies, particularly in labor unions, the educational system, and major ethnic organizations. Instead of focusing on Pennsylvania's right-wing politicians (the sort represented nationally by Senator Joseph McCarthy), Jenkins emphasizes the anti-Communist activities of liberal politicians, labor leaders, and ethnic community figures who were terrified of Communist encroachments on their respective power bases. He also stresses the deep roots of the state's militant anti-Communism, which can be traced back at least into the 1930s.