Reviewed by: Challenging Beijing's Mandate of Heaven: Taiwan's Sunflower Movement and Hong Kong's Umbrella Movement by Ming-sho Ho Kevin Wei Luo (bio) Ming-sho Ho. Challenging Beijing's Mandate of Heaven: Taiwan's Sunflower Movement and Hong Kong's Umbrella Movement. Philadelphia: Temple University Press, 2019. xvi, 269 pp. Paperback $39.95, isbn 978-1-4399-1707-7. How do we draw general lessons from exceptional historical events? This question is implicitly at the heart of Ming-sho Ho's path-breaking comparative study of Taiwan's Sunflower Movement and Hong Kong's Umbrella Movement, one of the first book-length projects of its kind since the tumultuous months of 2014. Brimming with rich empirical insights and ethnographic detail, the book takes a comparative angle to analyzing the "origins, processes, and outcomes" (p. 3) of the two movements, while seriously engaging with the broader literature of social movement theory. Ho sets out to address six puzzles in this book (pp. 8–10): 1. How radical movements emerged in seemingly conservative Confucian societies; 2. How both movements materialized not because of apparent political opportunities, but rather due to perceived threats; 3. How both movements were led by inexperienced student leaders; 4. How material resources did not seem to pre-determine the organizational capacity of the movements themselves; 5. How improvisation and "unsolicited" contributions played key roles in movement organization; 6. How the political fates of activist groups in Taiwan and Hong Kong diverged in the electoral arena in the aftermath of the protests. Successfully answering one central puzzle in a book monograph is already a tall order. Some of these questions—such as the movements' relationships with conservative Confucian political cultures and their impact on electoral outcomes post-2014—probably warrant entirely separate book-length projects down the road. Where Ho succeeds, however, is to embed the rest of the puzzles in three broader theoretical issues: organization and networks (primarily chapter 3, but also chapters 4–6), political opportunities and threats (chapters 4 and 5), and movement improvisation (chapter 6). This review aims to further highlight the immense theoretical and comparative potential of this [End Page 212] book, that should deserve more attention from scholars of political sociology and East Asian politics alike. Organization and Networks: The Strength of Weak Ties The networks of civic activist groups in Taiwan and Hong Kong played instrumental roles in explaining social movement mobilization for Ho. Counterintuitively, however, Taiwan's Sunflower movement emerged as relatively centralized and unified despite enjoying less financial support and lacking a strong leadership structure prior to mass mobilization. On the other hand, despite stronger institutionalization and resources possessed by the Hong Kong Federation of Students (HKFS) and the Occupy Central with Love and Peace (OCLP) campaign, the Umbrella Movement in Hong Kong suffered from internal dissent and lack of coordinated leadership (p. 144). From the conventional perspective of social movement theory this is certainly unexpected, as one would assume the prior level of institutionalization to be correlated with stronger capacities for movement coordination (pp. 138–140). Yet Taiwan's looser and overlapping ties among its student activist groups and NGOs (pp. 82–83) likely helped to generate more confidence in the ad hoc organizational structure of the Sunflower movement, and enabled more inclusive buy-in from movement participants. This is where the comparative research design of the book becomes indispensable. While critics had previously attributed Umbrella Movement's dysfunctions to the lack of organizational power, Ho shrewdly points out that prior organizational capacity in Hong Kong was fairly solid compared to that of Taiwan's, and thus cannot be the sole causal factor in explaining its leadership ineffectiveness (p. 144). Furthermore, while the Sunflower Movement did experience some ideological fragmentation among its ranks, fringe and militant elements within the movement still gave leaders the benefit of the doubt and did not seek to usurp movement leadership, primarily because of the strong levels of trust derived from overlapping social ties (pp. 170–172). Comparatively, activists in Hong Kong faced tougher obstacles in reconciling internal differences. Civic Passion—the militant wing of the movement—fervently challenged the legitimacy of the command center in Admiralty. Ho finds that this...