A groundbreaking history of political struggle in the Spanish New World, where commoners and elites alike challenged the social order through the remarkable power of paperwork. As Spanish conquistadors swept through the New World, the Crown envisioned that a rigidly hierarchical aristocratic order would flourish in their wake. At first, this vision seemed to be within reach: the great conquistadors ruled as noblemen over millions. Yet contrary to all expectations, the Spanish empire in the New World quickly became a hotbed of radical efforts to overturn the emerging order. With the conquistadors in retreat, new enclaves controlled by powerful friars and native lords arose. But they too collapsed, again to the surprise of many. As Jorge Cañizares-Esguerra and Adrian Masters show, these social orders broke down thanks to the challenges mounted by countless individuals across the Spanish Americas—including non-elite Spanish and Indigenous people, women, and the enslaved. To achieve their goals, they turned not only to outright violence but also to massive amounts of paperwork: petitions, complaints, lawsuits, and secret testimonies. Through this grassroots “lawfare,” vassals undercut the emerging seigneurial dynasties of the conquistadors, stripped the friars of theocratic authority, and curtailed the might of native lords. Collectively, they spearheaded movements against tyranny and slavery, proposed and challenged laws, produced new types of knowledge, created archives and historical accounts, and questioned the nature of truth itself. In the process, however, these actors also gradually co-created a lasting new society of orders—one that would solidify in the 1570s with viceroys, bishops, and inquisitors at its apex. Dramatically recasting a pivotal era in colonial history, The Radical Spanish Empire illuminates how the power of paperwork forever transformed the New World.