American Indians and their traditions are a vital nexus of religion and ecology. Even postcolonial native movements that incorporate various Christian traditions are typically grounded in the natural world. Toward the end of the nineteenth century, ethnologist James Mooney happened upon one such phenomenon while conducting research in Indian Territory. Several Southern Plains tribes had taken up the sacramental use of peyote, a small, spineless cactus endemic to the southern Rio Grande Valley and northern Mexico. Various oral accounts attribute the origin of modern peyote religion to a woman. Mooney lrst witnessed Peyote Woman's ceremony in February 1891, when he was invited to a riverside encampment several miles west of Anadarko, Oklahoma. Peyote Woman and her followers made quite an impression on Mooney. Peyote may be the indispensable element of practicing its namesake religion, but the key to understanding and interpreting this tradition is Peyote Woman.