In this careful study, Daniel Sack (now a senior program officer at the National Endowment for the Humanities) recovers the history of a group with which most people, even most students of American twentieth-century history, are completely unfamiliar. The group eventually known as Moral Re-Armament was founded in 1919 by Frank Buchman, a Lutheran minister with a particular faith in the possibility of ending suffering in the world by the tireless promotion of personal change and moral probity. Buchman organised various iterations of the group to push the idea of listening to God and adhering to what he called the four absolutes: absolute love, absolute purity, absolute honesty and absolute unselfishness (p. 89). At its height, Buchman's movement had headquarters on three continents, over a thousand full-time volunteers, and designs on somehow being made official government policy in several countries. If the group's vague feel-good ethic leaves readers wondering what exactly that would have meant, Sack suggests that many contemporaries had the same difficulty. ‘Sure I'm for Moral Re-Armament, whatever that is’, one government official said in 1939, ‘It's just like being against sin’ (p. 112). Sack finds an inherent capacity for reinvention and adaptation to be the defining characteristic of MRA's history, and these are double-edged weapons for a religious group, often promoting both short-term success and long-term confusion about identity and purpose. Buchman died in 1961, and MRA faltered in ensuing years. The significance of Sack's study lies in his demonstration of how novel communications strategies were deployed in the twentieth century by groups like MRA, and also in the movement's descendants. Though forgotten in name, the influence of Moral Re-Armament nevertheless reverberates in two movements that it helped birth: ‘Up with People’ – now an international humanitarian program focused on music and performance – was originally an MRA youth-outreach program. More significantly, MRA's emphasis on ‘personal change, story-telling, and making amends’ persists today in Alcoholics Anonymous, founded in the 1930s by men influenced by Buchman (p. 4). Because AA has exerted a significant influence on other contemporary recovery groups, Sack's reconstruction of MRA's history is a valuable step toward a better understanding of the religious and moral underpinnings of such movements.