In this Yale lecture, Professor Beverly Gage covers the aftermath of the Second World War, tracing how postwar prosperity in the United States coexisted with a growing fear of communism. The class walks through the origins of the Red Scare and the construction of a new national security state in response to Cold War anxieties. Recorded as part of the DeVane Lecture series America at 250: A History, the lecture is part of a one time course tracing United States history from 1776 to the present across lectures by three Yale historians, following directly from the prior class's treatment of the Second World War.