Leonard had been ill for some time, the San Francisco Chronicle reported. He continued to run workshops at Integral Transformative Practice, the institute he founded in Mill Valley, Calif., until shortly b before his death.
A native of Macon, Ga., Leonard had lived in the San Francisco area since 1957. He first covered the human potential movement for Look and then embraced it, especially after he left the magazine in 1970.
He became an advocate of the Esalen Institute and a fifth-degree black belt in aikido.
In addition to teaching at Esalen, Leonard wrote many books, including "Education and Ecstasy," "The Transformation," "The Ultimate Athlete," "Mastery" and "The Life We Are Given."
"He was a tremendous social observer. He was a guide for us," Michael Murphy, founder of Esalen, said. "He saw California as a window to the future, and he was right."
Leonard is survived by his wife, Annie, three daughters and six grandchildren.