While almost everyone in Japan regularly participates in traditional activities that are religious and spiritual in nature, it is perplexing that only 20 to 30% of the population self-identify with a particular religion. Several accounts have been offered to explain this discrepancy, but these speculations had never been examined empirically. There are several reasons as to why Japanese empirical scientists ignored the topic for so long. One may be that Japanese scientists themselves are too accustomed to the tradition to reflect upon the discrepancy. Since even astute researchers may fail to recognize such a fertile field for empirical research, the opportunities and venues to pursue this line of research in Japanese academia have been scarce. The Empirical Study of the Psychology of Religion and Spirituality in Japan is a translated version of the original book, a collection of chapters by scholars from different psychological disciplines. It is the first book with an emphasis on empirical perspectives on the topic. Thus, it is also the first book written in English in the field. This book offers not only detailed empirical data, but also an examination of the theories and ideologies that underlie contemporary understanding of religion and spirituality in Japan.