I found this not the easiest book to read, but a very strong case, thoroughly researched. It is written by a psychiatrist whose patient had spontaneous memories of living as a Cathar (a Christian sect which believed in reincarnation) in 13th-century France. Because these people were persecuted during the Inquisition, and because the Inquisitors kept careful notes, the memories could be verified historically to a degree rarely found in this kind of case. Note that the patient had some of these memories as a schoolgirl, and wrote them down many years before she met the author. The identity of not just one, but several persons who figure in this woman's past-life memories were verified as having actually lived.
Cathars & Reincarnation makes several valuable contributions to the field of reincarnation studies. Firstly, it gives us a first-hand glimpse of a branch of Christianity which accepted reincarnation, and was persecuted for it. Secondly, it shows how reincarnation has been forceably and violently suppressed in our culture, and why we have inherited the attitudes we have. Thirdly, because this case does not rely on hypnosis, and because there are so many historically-verifiable details recalled by a school-girl who would not have had access to the information through normal means, it counters the twin objections that past-life memories are solely a result of hypnotic suggestion or cryptamnesia.
I strongly suspect that many of the people who lived during the time of the Cathars are back with us today as advocates for re-introducing reincarnation to Western society. I'd recommend this book both for a better understanding of reincarnation history, and for the solid reincarnation case it presents.