Like many of the founders of AIM, Bellecourt was profoundly shaped by his experience of being stolen away from his family to church- or state-run schools. As a boy, he attended a Catholic school run by nuns from St. Benedict’s Mission. His hands bore the scars of a nun’s ruler. He often cut class, escaping to nearby forests and lakes for hunting and fishing. Later, a judge sentenced him to a correctional school off-reservation for truancy. In the book The Thunder Before the Storm which he co-wrote with Jon Lurie, Bellecourt recounts being sexually abused by a Catholic priest and forced into hard labor.
When he was sixteen, his family moved to Minneapolis, where Bellecourt dropped out of high school and struggled to find a job. He turned to drinking, burglary, and robbery and was jailed. At Stillwater Prison, after a harrowing stint in solitary confinement, he met Eddie Benton-Banai, an Ojibwe from Wisconsin. The two began running cultural programs and sweat lodge ceremonies for Native inmates. The Indian Folklore Group, as it was known, taught Native history and language. For the first time in the prison’s history, spiritual leaders were allowed to conduct Midewin ceremonies and purification rites that Bellecourt described as leading him “down a healing path.” Reconnecting with culture and spirituality was transformative for him and hundreds like him. “There was an Indian renaissance going on in that prison,” he recalled.
After his release in mid-1968, Bellecourt teamed up with former inmates, including Benton-Banai and a charismatic Ojibwa named Dennis Banks, to “transpose our Native American studies program to the streets of Minneapolis.” They formed the American Indian Movement that July with others like Pat Bellanger, Annette Oshie, Harold Goodsky, and George Mitchell. Bellecourt was its first chairman. AIM started out as a community forum, where Native people brough their problems and complaints about police, schools, housing, jobs, and discrimination. Their quick response and organizing earned them the respect of their base. Bellecourt had worked for a utility company after prison, but he soon quit to dedicate himself full-time to the movement. While protesting the Vietnam War, he met his future wife Peggy Sue Holmes, the daughter of an Anishinaabe woman and a Japanese man who was once interned in a war relocation camp. They had four children together.