This article complements existing scholarship on religious transformation in Guatemala's western highlands by focusing on the important and often overlooked role played by Maryknoll women religious. The Maryknoll Sisters' hospital in Jacaltenango in the department of Huehuetenango became the center of a medical program that included eighteen clinics, a nursing school, a midwifery program, and a health promoters program. Mayas selectively embraced Maryknoll Sisters'medicine and actively sought opportunities to disseminate it. Evenas Maya health promoters and midwives introduced "Western" preventative and curative medicine and promoted a Romanized practice of Catholicism, they transformed the Maryknoll Sisters' medical programs to parallel an existingMaya leadership composed of chimanes and mid wives responsible for rituals of faith and healing. Mayas appropriated, interpreted, and synthesizedMaya and Catholic religious concepts and practices with Maya and Western health-care practices and beliefs. By incorporating Maryknoll women religious and their medical programs into studies of religious transformation in Guatemala's western highlands, we gain new insight into this process of change and into the central role that womenplayed in it.