The Third Disestablishment: Church, State, and American Culture, 1940–1975 examines the formative period in the development of modern church–state law. It discusses the cultural background for the Supreme Court’s adoption of separation of church and state as the controlling constitutional construct and then the popular response to that adoption. This cultural backdrop included a period of heightened tensions between institutional Protestantism and Catholicism, a conflict that did not dissipate until after the election of John F. Kennedy and the reforms of Vatican II. The book then considers the decline of church–state separation as a legal principle and a cultural value, a process that began in the 1960s with the rise of social welfare legislation under the Great Society.