This article aims to explain the failure of the DPP government’s anti-nuclear policy. We begin with an overview of the literature on social movements in order to locate the key factors affecting the outcome of collective action. Social mobilization, reform opportunity and political strategy turn out to be significant in this regard. In sum, the success of movement consists in a delicately combined circumstance. Sustained social mobilization is necessary, but not sufficient. The capacity of reformer to grasp the opportunity and adopt a viable strategy to orchestrate a reform coalition, to engineer the urgency for reform, and to take political initiative could not be overlooked. The latter part of this article reconstructs the evolution of the anti-nuclear reform after March 2000. We find (1) the resuscitated popular mobilization in the year 2000 contributes to the pressure for reform; (2) the downfall of the KMT and formation of a reform-oriented government bright forward a valuable reform opportunity; (3) the DPP’s adventurist strategy fails to organize the pro-reform camp while arousing the dogged resistance of the privileged and its enemy. We conclude by rethinking the future agenda of progressive politics and reforms in Taiwan.