To create a festschrift in honor of a scholar as important asCharles Tilly is a daunting task. To their credit, the editors and authors ofChallenging Authority successfully provide a thoughtful andparticularly readable glimpse into both the past and the future of the study ofcontentious politics, a field in which Tilly's contributions have beenundeniably crucial. From more traditional interpretations of Tilly's workto innovations in chapters by Kim Voss and Marc W. Steinberg, this volumedisplays the wide array of applications and insights provided by the politicalprocess model for studying collective action, whether in medieval Spain or 1989China. However, the volume moves only in fits and starts toward the new“relational structuralism” (xix) that the editors herald ascoalescing around the study of collective action.