Analysts of social movements habitually conceive of political mobilization as a collective action problem, potentially misleading analysts about the nature of the conflicts. Collective action mobilizes individuals to pursue interests shared by a given group. Collective behavior is mobilization that undermines shared interests and splits existing groups, leading to unintended and collectively destructive outcomes. This article recounts several of the author’s research projects into political upheavals in Mao-era China, in which movements initially thought to be a form of collective action focused by network ties turned out to be a form of collective behavior that undermined structurally strong dictatorships and the interests of their beneficiaries. The research revealed the hidden vulnerabilities of strong network ties and seemingly impregnable authoritarian structures built on them.