Midewiwin, or Grand Medicine Society, is a book about a religious society found among the Algonquian of the Upper Great Lakes (Anishinaabe), northern prairies, and eastern subarctic areas of Canada. The community is famous for practicing unique healing methods and a secretive way of organization, although they are open to society and give services to people from outside their community. The book tells about the beliefs, rituals, and origins.

Tribal peoples believe that the shaman experiences, absorbs, and communicates a special mode of power, sustaining and healing. This book discusses American Indian shamanic traditions, particularly those of the Woodland Ojibway, in terms drawn from the classical shamanism of Siberian peoples. Using a cultural-historical method, John A. Grim describes the spiritual formation of shamans, male and female, and elucidates the special religious experience that they transmit to their tribes. Writing as a historian of religion well acquainted with ethnological materials, Grim identifies four patterns in the shamanic experience: cosmology, tribal sanction, ritual reenactment, and trance experience. Relating those concepts to the Siberian and Ojibway experiences, he draws on mythology, sociology, anthropology, and psychology to paint a picture of shamanism that is both particularized and interpretative. As religious personalities, shamans are important today because of their singular ability to express symbolically the forces that animate the tribal cosmology. Often identifying themselves with primordial earth processes, shamans develop symbol systems drawn from the archetypal earth images that are vital to their psychic healing technique. This particular ability to resonate with the natural world is felt as an important need in our time. Those readers who identify with American Indians as they confront modern technological society will value this introduction to our native shamanic traditions and to the religious experience itself. The author's discussion of Ojibway practices is the most comprehensive short treatment available, written with a fine poetic feeling that reflects the literary expressiveness inherent in American Indian religion and thought.

Shamanism can be defined as the practice of initiated shamans who are distinguished by their mastery of a range of altered states of consciousness. Shamanism arises from the actions the shaman takes in non-ordinary reality and the results of those actions in ordinary reality. It is not a religion, yet it demands spiritual discipline and personal sacrifice from the mature shaman who seeks the highest stages of mystical development.

The Midewiwin is the traditional religious belief system central to the world view of Ojibwa in Canada and the US. It is a highly complex and rich series of sacred teachings and narratives whose preservation enabled the Ojibwa to withstand severe challenges to their entire social fabric throughout the 19th and 20th centuries. It remains an important living and spiritual tradition for many Aboriginal people today.The rituals of the Midewiwin were observed by many 19th century Euro-Americans, most of whom approached these ceremonies with hostility and suspicion. As a result, although there were many accounts of the Midewiwin published in the 19th century, they were often riddled with misinterpretations and inaccuracies.Historian Michael Angel compares the early texts written about the Midewiwin, and identifies major, common misconceptions in these accounts. In his explanation of the historical role played by the Midewiwin, he provides alternative viewpoints and explanations of the significance of the ceremonies, while respecting the sacred and symbolic nature of the Midewiwin rituals, songs, and scrolls.