Since the late 1990s, research on social movement outcomes has proliferated. Most studies have focused on policy outcomes, but other structural, organizational, and biographical consequences have also been identified. A still underexplored domain is the impact of unintended consequences on movement dynamics. Social movements do not always produce the outcomes that they intended, and these unintended consequences can influence movement dynamics in unexpected but significant ways. In this case study of the Korean women's movement, I find that(1) collective actors tend to respond more quickly when they are faced with outcomes that differ from their original plans or intentions; as a consequence they choose or are forced to modify their organizational infrastructures, which in turn shifts the movement's dynamics;(2) the impact of unintended consequences is mediated by collective actors' framing, and subjectively evaluated(not objectively judged) collective action outcomes are pertinent to movement dynamics; and(3) when unintended consequences are viewed negatively they sometimes provide momentum for movement revitalization.