James Bryant Conant issued his famous report, "The American High School Today," in 1959, giving voice to a clear and influential reaffirmation of the comprehensive secondary school. Conant's vision in this, and in another work, "Slums and Suburbs" (1961) makes an interesting point of departure for consideration of the forces that have shaped the U.S. high school in the latter half of the 20th century. This paper discusses Conant's ideas and addresses just how these ideas have been treated by history. First the paper provides the historical context of the post World War II United States, and then it examines in depth the questions of race and the comprehensive high school; the rise of a youth culture; and high schools, youth, and the changing urban economy. The paper assesses how the changing social and economic context of postwar U.S. society changed the prospects for success of the comprehensive high school. It concludes that a number of historical developments converged in the decades following the Second World War to make James Conant's vision of the high school problematic, at least in the nation's large metropolitan areas. It also questions what the best institutional arrangement is for the great variety of U.S. youth to be educated in the coming century. Contains 4 tables of achievement, enrollment data, and 85 references. (BT)