The mendicant orders—Augustinians, Carmelites, Dominicans, Franciscans, and several other groups—spread across Europe apace from the early thirteenth century, profoundly influencing numerous aspects of medieval life. But, alongside their tremendous success, their members (or friars) also encountered derision, scorn, and even violence. Such opposition, generally known as antifraternalism, is often seen as an ecclesiastical inhouse affair or an ideological response to the brethren’s laxity: both cases registering a moral decline symptomatic of a decadent church. Challenging the accuracy of these views, The Making of Medieval Antifraternalism contends that the phenomenon exhibits a breadth of scope that, on the one hand, pushes it far beyond its accustomed boundaries and, on the other, supports only tenuous links with Reformation or modern forms of anticlericalism. Based on numerous sources, from theological treatises, to poetry, to criminal court records, this study shows that people from all walks of life lambasted and occasionally assaulted the brethren, orchestrating in the process detailed scenes of urban violence. Their myriad motivations and diverse goals preclude us from associating antifraternalism with any one ideology or agenda, let alone allow us to brand many of its proponents as religious reformers. At the same time, it demonstrates the friars’ active role in forging a medieval antifraternal tradition, not only by deviating from their founders’ paths to varying degrees, but also by chronicling their suffering inter fideles and thus incorporating it into the orders’ identity as the vanguard of Christianity. In doing so, The Making of Medieval Antifraternalism illuminates a major chapter in Europe’s social, urban, and religious history.