According to traditional Navajo belief, seizures are the result of sibling incest, sexual witchcraft, or possession by a supernatural spirit--associations that have kept such disorders from being known outside Navajo families. This new study is concerned with discovering why the Navajos have accorded seizures such importance and determining their meaning in the larger context of Navajo culture. The book is based on a 14-year study of some 40 Navajo patients and on an epidemiological survey among the Navajos and among three Pueblo tribes.