In today’s Iran, it is difficult to pinpoint a sphere in which Islamic Revolution Guard Corps (IRGC) does not have direct or indirect role and influence. IRGC has become an indispensable power broker despite having one of the most marginal roles in the constitutional structure of the Islamic Republic. This paper examines IRGC’s trajectory of expansion from an agile task force of young revolutionaries to a multidivisional cluster of military and civilian units. The common trend in scholarship offers a deterministic explanation for this rapid expansion. However, we argue that the institutional and functional advancement of IRGC has been historically contingent upon a series of political conflicts that–through a dialectic of (perceived) internal and external threats and opportunities–demanded ad-hoc and improvised responses, and generated spontaneous spaces for the Corps to step in. Applying a tailored Outcomes Harvesting methodology, we look at the organization’s growth in size and in the scope of its activities, and demonstrate that these developments go beyond any deliberate state agenda. In fact, on several occasions, Iran’s civil administration attempts to normalize and regulate the machinery of the state, and to tranquilize the revolutionary energy, paradoxically led to further concentration of power into IRGC’s hands. Iran’s major political camps have tried at different times to tame, confine, discipline and even dissolve it. At the same time, other state institutions have fiercely competed with IRGC over scope of responsibilities and extent of authority. Furthermore, there have been several rounds of infightings and shakeups within IRGC, and the internal dynamism of this entity has proven ripe for generating new political cleavages. Nonetheless, IRGC not only has persevered but also has grown bigger and stronger. This has not always been the case for other experiments of institution-building in post-revolutionary Iran, as those entities either did not last long or their powers and authorities shrank over time. The existing literature often attributes IRGC’s hegemony to its coercive power. But we argue that hegemony also entails gaining and securing the acquiescence to IRGC’s presence, by which the business, cultural and political elite signal consent to be co-opted.