When Movements Matter: The Townsend Plan and the Rise of Social Security. By Edwin Amenta. Princeton: Princeton University Press, 2006. 352p. $35.00.

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

Do movements matter? In particular, can they extract policy concessions from state actors? And if so, how? These questions have been the focus in recent years of a burgeoning and exciting literature. For Frances Fox Piven, the answer to the question “Do movements matter?” is an emphatic yes. Indeed, she argues that the principal surges in egalitarian social change in American history can be traced directly or indirectly to the intervention of disruptive protest movements. For Edwin Amenta, the answer is also yes, but in a more qualified fashion. Together, these two works are brimming with insights regarding how movement impact might be understood.