Converts are often odd, and Oppenheimer’s engaging study of six prominent left-wingers who wound up on the right illustrates the eccentricities that have made people such as Whittaker Chambers (Soviet sympathizer and spy turned anticommunist conservative), David Horowitz (Black Panther supporter turned right-wing crusader) and Christopher Hitchens (antiwar socialist turned Iraq war cheerleader) almost as irritating to their new associates as they were to their old ones. But the 70 years between Chambers’ work with the Soviet spy apparatus and Hitchens’ support for the Bush administration saw such profound changes in the structure of U.S. politics that Oppenheimer’s attempt to place these six conversion stories in a common frame is less illuminating than one might hope. (The writer and critic Norman Podhoretz, the political theorist James Burnham, and Ronald Reagan are also included.) The left from which Chambers and Burnham seceded during the Cold War was an organized political force seeking a revolutionary transformation of American life. The left that Hitchens abandoned was less organized and less coherent. The difference between leaving the two was a bit like the difference between forsaking the Catholic Church and going home early from a dinner party. Podhoretz was the last to leave the Old Left, and Horowitz the first to leave the New Left; a closer focus on the similarities and differences between their experiences would have shed more light on the shifts in American political and intellectual life over the last generation.