This paper presents a theory of military insubordination in Middle Eastern authoritarian regimes having witnessed large-scale, anti-incumbent popular mobilization. The aim is to distinguish between different types of insubordination. The Arab Spring serves as an apt empirical laboratory for such an analysis. Conceptually I distinguish between military agents, namely higher officers vs. rank-and-file soldiers, and between military personnel's collective vs. individual action. Based on original empirical research, I identify four types of military insubordination: coups d'état as collective action of officers (Egypt 2011, 2013); mutinies as collective action of soldiers (Yemen 2011, 2014); defection as individual officer action (Tunisia 2011); and desertion as individual action of soldiers (Syria 2011-2012). I advance three theoretical claims: First, domestic shocks are a necessary precondition for individual military insubordination. Second, popular mass uprisings are surprising events and shorten the time horizon for officer coordination of military insubordination. Hence, coups d'état as coordinated action occur only when mechanisms of officer coordination exist prior to the uprisings. Third, mutinies occur if military agents have established horizontal cohesion across army ranks prior to the uprising. This paper is part of a book project and relies on the author's field research in Egypt, Tunisia, and Yemen as well as on research on the Syrian case conducted in Lebanon and Turkey. An original dataset on coups d'état in Middle East, 2050-2013, complements the paper's empirical foundation.