Drawing on an in-depth historical study of store-opening competition between two retail organizations, we re-conceptualize interfirm rivalry to consist of routinized competitive actions. The routine-based view of rivalry that emerges from our findings has several characteristics that have not received sufficient attention in the literature. For example, executives contribute to the firm’s competitive maneuvers by developing and nurturing what we term competitive action routines rather than directly. Moreover, competitive inertia stems from the organization’s architecture rather than from the routinization of competitive actions per se. Finally, intensifying competition favors an increasingly routinized rather than improvised approach to competition, as it allows the firm to rapidly capture contested opportunities.