For centuries, a persistent and important component of Lakota religious life has been the Inipi, the ritual of the sweat lodge. The sweat lodge has changed little in appearance since its first recorded description in the late seventeenth century. The ritual itself consists of songs, prayers, and other actions conducted in a tightly enclosed, dark, and extremely hot environment. Participants who "sweat" together experience moral strengthening, physical healing, and the renewal of social and cultural bonds. Today, the sweat lodge ritual continues to be a vital part of Lakota religion. It has also been open to use, often controversial, by non-Indians. The ritual has recently become popular among Lakotas recovering from alcohol and drug addiction. This study is the first in-depth look at the history and significance of the Lakota sweat lodge. Bringing together data culled from historical sources and fieldwork on Pine Ridge Reservation, Raymond A. Bucko provides a detailed discussion of continuity and changes in the "sweat" ritual over time. He offers convincing explanations for the longevity of the ceremony and its continuing popularity. Raymond A. Bucko is an associate professor of anthropology at Le Moyne College.