Bringing together insights from macro-level theory about "mass imprisonment" and micro-level case studies of contemporary punishment, this article presents a mid-level agonistic perspective on penal change in the USA. Using the case of the "rise and fall" of the rehabilitative ideal in California, we spotlight struggle as a central mechanism that intensifies the variegated (and sometimes contradictory) nature of punishment and drives penal development. The agonistic perspective posits that penal development is fueled by ongoing, low-level struggle among actors with varying amounts and types of resources. Like plate tectonics, friction among those with a stake in punishment periodically escalates to seismic events and long-term shifts in penal orientations, pushing one perspective or another to the fore over time. These conflicts do not occur in a vacuum; rather, large-scale trends in the economy, politics, social sentiments, inter-group relations, demographics, and crime affect—but do not fully determine—struggles over punishment and penal outcomes.