This second edition includes a new preface by professor emeritus in psychology, Dr. Charles T. Tart. The book covers one of the most exciting research eras in psychology and psychiatry"the use of psychedelic drugs and their ramifications for exploration of the mind"is discussed with emphasis on the connection of ESP to psychedelics and our transpersonal nature. As Dr. Tart states, this study remains as important today as when it was first published, and will hopefully guide a new generation of researchers to finding the knowledge we need!