Ian Stevenson, a psychiatrist at the University of Virginia, has devoted his career to the study of cases suggestive of reincarnation. The cases consist of narratives of young children who claim to remember past lives. The cases occur primarily in India, Sri Lanka, South Asia, West Africa, Lebanon, and among Northwestern Native Americans, in cultures and religions in which reincarnation is accepted. Stevenson and his colleagues have collected over 2000 such narratives, but only a much smaller number provide what he considers "strong" evidence.

In the latter cases, Stevenson has performed detailed, nearly contemporaneous investigations that appear to rule-out communication of any kind between the child's family and the relatives of the recently deceased person the child claims to be. In addition, many of the "strong" cases have birth defects or birthmarks at the exact sites of traumatic injuries in the deceased person's life.

This book is a shortened and popularized version of a scientific monograph entitled Reincarnation and Biology: A Contribution to the Etiology of Birthmarks and Birth Defects (also published by Praeger Press in 1997). Stevenson categorizes his cases by strength of evidence for a precisely located traumatic injury in the deceased person (i.e. simply remembered by the family, identified in medical records, or verified at autopsy). He also categorizes cases by the size and nature of the child's defect or birthmark.

In each chapter he presents a series of short narratives summarizing cases in a particular category, and comments on the weight and possible interpretations of the evidence. In Chapter 26 Stevenson analyzes a variety of explanations (including normal and paranormal possibilities), and concludes that the strongest of his cases are best explained by accepting the hypothesis of reincarnation (i.e. the discarnate personality of a recently dead person influencing the personality of a newborn child).