In the wake of the Second Vatican Council, Mexican traditionalist Catholics mobilized in apparent unity against Catholic “progressivism” and the Left. Yet, they succumbed to their own internecine fights. This article examines the conflicts within Mexico's post-Cristero Right during the 1960s and 70s by tackling the ruptures and realignments surrounding the excommunication of Fr. Joaquín Sáenz Arriaga, a traditionalist Jesuit famed for attacking conciliar reforms and the legitimacy of Paul VI's papacy. I argue that the ensuing debates put into question the apparent coherence of conservatives in the face of social unrest after 1968, highlighting the long-standing entropy of right-wing Catholicism, as traditionalists clashed over matters of orthodoxy, Catholics’ historical relationship with the postrevolutionary state, and the contested memory of the Cristero War, which they used to legitimize their positions and define the terms of their traditionalism. Using anticommunism and anti-Semitism to wage their battles, these traditionalists occupied important spaces in the public sphere, contributed to Mexico's Cold War polarizations, and shaped the Mexican Right's international outlook. Their conflicts attest to the contentious plurality of the Mexican Right during this period, which invites further study to better understand how these actors situated themselves in a rapidly changing world.