Abstract: The last two decades have seen an accelerated production of novel devotions at the margins of the Catholic Church in Mexico. Celebration of Santo Niño Jesús Doctor, the infant Jesus dressed as a medical doctor, is one of the fastest-growing new religious expressions in contemporary Mexico. This paper takes this particularly productive moment as an opportunity to theorize novelty and innovation in Mexican religion. In spite of the increase in non-Catholic religious alternatives, including most importantly a range of novel Protestant expressions, I suggest the possibility that at the beginning of the twenty-first century Roman Catholicism is the primary field of religious innovation in Mexico, and that it frequently has been an important locus of innovation since its arrival in the New World. An analysis of devotion to this new manifestation of the infant Jesus reveals the cultural mechanisms that allow for and sustain religious innovation in Mexico.