At the conclusion of his military service in 1946, he joined the faculty of
Harvard University. There, he became one of Harvard's most popular and iconic professors, teaching its undergraduates "Western Thought and Institutions" for more than three decades, a course that covered European history, philosophy, and politics by examining six of history's revolutions in great detail—the twelfth century clash between church and state that resulted in
Magna Carta; the Protestant Reformation of the early sixteenth century; the English revolution of the mid-seventeenth century; the French Revolution; the British Age of Reform of the early nineteenth century; and the rise and fall of Nazi Germany in the twentieth century. His 1956 book,
Treasury Control, documented fiscal policy in the UK. In 1965,
British Politics in the Collectivist Age considered the conflict between liberal and conservative approaches in the UK following World War II.
Britain Against Itself: The Political Contradictions of Collectivism (1982) analyzed the UK in the Thatcher era. He focused on the US in
To Make a Nation: The Rediscovery of American Federalism (1993) about American political theory. Following his retirement from Harvard in 1982, Beer served on the faculties of both
Boston College and
Dartmouth College. He was also a senior scholar at the
Woodrow Wilson International Center for Scholars. ==Cultural notes==