This article investigates Tilly's (1978) long-neglected question of how collective action outcomes modify agents' interests and movement dynamics. A case study of the Korean white-collar union movement demonstrates how the framing of collective action outcomes influences movement trajectories in two ways. First, actors' subjective evaluation of whether collective action succeeds or fails to attain movement goals alters movement dynamics by changing goals, strategies, tactics, action repertoires, and collective identities. Second, to whom the cause of the collective action outcome is attributed mediates these transformations. The evaluation of outcomes and attribution of causes is ongoing. They occur throughout the development of social movements and dynamically shape their trajectories. The case study confirms these observations: in early stages of collective action, when union members considered union efforts to improve their economic well-being fruitless and blamed government intervention for their failures, union activities evolved into political protest against the state and struggle for democratization. At a later stage, when agents successfully achieved economic and political goals and credited their union activism for the victory, union movements progressed by intensifying interunion solidarity.
