Social revolutions are a major historical feature of twentieth-century world history. For those countries in which they occurred, they became the axis on which their postrevolutionary histories revolved, acquiring a mythical character.This dissertation was completed at Harvard University under the supervision of John Womack. That these revolutions had created a better and more equitable world, that they had been a step towards progress, that without them, tyranny and injustice would have prevailed, became some sort of a religious faith difficult to question without being accused of heresy.