Previous explanations of the rapid development of the political opposition in Taiwan after 1986, when the Democratic Progressive Party (DPP) announce its establishment, tend to focus on the process of "political elite interactions" between the Kuomintang (KMT) and its challengers. The role of the change of popular support for the opposition were largely ignored. This paper addresses to the issue of why and how the DPP gains more popular support to launch a successful challenge after 1986 by comparing the ideology and the strategy of consensus mobilization utilized during the two waves of challenges in 1979 and 1986- 9 respectively. The determinants of the consensus mobilization this paper points out include: the degree of resonance between the opposition ideology and the life experiences and/or social memory of its potential supporters; timely occurrences of incidents that coinciding with the opposition ideology; the existence of opposition organizations; and the strategy of transmitting opposition ideology to its potential supporters. The 1979 opposition insurgency, whose primary goals were democratization of Taiwan, lead to a major setback when it met with severe repression in the "Kaohsiung Incident" at the year end. The radicalization of opposition ideology in the 1980s, which is marked by a set of new claims based on "Taiwanese Nationalism" instead of mere "democratization" in the previous era, along with the existence of an opposition organizational network, and the adaption of the mass movement strategy, are considered to be the major factors that distinguished its success from the 1979 insurgency. Ironically, the radicalization of the opposition challenge in terms ig ideology and strategy, though consciously resisted by the opposition leader before the 1980s, were fueled by the KMT's constant repression against the opposition, and further fertilized by the disadvantageous political power structure against native Taiwanese based on a set of "Chinese Nationalist Ideology," which gradually lost its power of appeal and legistimacy in the 1980s.