This essay is based on the author's talk at the FPRI Wachman Center's History Institute for Teachers on "What Students Need to Know about America's Wars, Part 2: 1920-Present," held May 2-3, 2009. Observing that the Vietnam War was the longest and most contested conflict in American history and that it called into question many widespread assumptions that Americans had held about their country, Spector advocates that it is difficult to identify with precision what students ought to know about the Vietnam War because much of what they probably ought to know about is subject to dispute. The author discusses the war in terms of several separate, though related and simultaneous, conflicts between 1965 and 1973, including: (1) Air war against North Vietnam and against the Ho Chi Minh Trail in Laos; (2) Ground war in South Vietnam waged by the North Vietnamese Army, the Americans, the South Vietnamese and the Viet Cong; (3) the "Other War" to establish South Vietnamese government control over the rural areas; (4) the "war at home," the growth of both organized and unorganized opposition to the war, the movement of public opinion, and the impact of those developments on American domestic politics; and (5) the diplomacy of the war involving negotiations between both primary combatants and, eventually, the Soviet Union and China. Comparing the denial, rationalization, and finger-pointing triggered by the Vietnam War to other disasters in American history, including the Civil War, the Great Depression, and Pearl Harbor, Spector concludes that Americans do not like stories without happy endings or problems without solutions.