How do insurgents engaged in high-risk collective action maintain solidarity when faced with increasing costs and dangers? Based on a combination of process tracing through qualitative evidence and an event-history analysis of a unique data set assembled from naval archives concerning a mass mutiny in the Royal Navy in 1797, this article explains why insurgent solidarity varied among the ships participating in the mutiny. Maintaining solidarity was the key problem that the organizers of the mutiny faced in confronting government repression and inducements for ships’ companies to defect. Solidarity, proxied here as the duration of a ship’s company’s adherence to the mutiny, relied on techniques used by the mutiny leadership that increased dependence and imposed control over rankand- file seamen. In particular, mutiny leaders monitored and sanctioned compliance and exploited informational asymmetries to persuade seamen to stand by the insurgency, even as prospects for its success faded.