Social Movements and Organization Theory. Edited by Gerald F. Davis, Doug McAdam, Richard Scott, and Mayer N. Zald. New York: Cambridge University Press, 2005. 452p. $80.00 cloth, $36.99 paper.

Challenging Authority: How Ordinary People Change America. By Frances Fox Piven. Lanham, MD: Rowman & Littlefield, 2006. 200p. $21.95.

These two books, both important additions to the social movement literature, represent two traditions at theoretical odds. Frances Fox Piven's new book is an authoritative, updated restatement of Piven and Richard Cloward's classic thesis that it is not lasting organization but fleeting and overwhelming mass disruption—literally, “the mob” in her new work—that is the only source of progressive reform in American politics. Meanwhile, the focus of Gerald Davis et al.'s new book is squarely in the organization-centered tradition of social movement scholarship. And yet, while the books are quite different, Doug McAdam and Piven (with Cloward) were all pioneer scholars of the role of political opportunity on movement emergence and outcomes. These two books are testimony to how far research on social movements has come in the past 35 years.