The quintessential textbook on reincarnation, both scholarly and readable. Sylvia Cranston (nom de plum for Theosophist Anita Atkins) distills her vast resources and and inside information, gained from a lifetime of involvement with the Theosophical Society, into a clear, insightful presentation. She also writes compellingly on the detrimental effects that materialism has had on our Western society, and how embracing a reincarnationist view would help to heal many of these social problems. If you want a strong introduction to the topic, I recommend starting here.