The macabre mass suicide by adherents of the Heaven's Gate Cult in 1997 was shocking and difficult to comprehend for most outsiders. Their bizarre mindset, which mixed New Age religion with belief in extraterrestrial visitation, struck many as unique. In fact, as the contributors to this intriguing study show, the belief in alien contact has had religious overtones since the first purported sighting of an unidentified flying object (UFO) in 1947. Moreover, the religious dimensions of the UFO phenomenon may be the key to understanding the widespread appeal of this modern craze. An expert in new religions, Professor James Lewis has here brought together twenty insightful articles that cover the many variations of UFO-based religions. What the contributors demonstrate is that there are persistent and salient themes underlying the diversity of beliefs centered on the UFO phenomenon. Hearkening back to theosophy, many groups have interpreted UFO sightings and alleged contacts as attempts by alien ambassadors from a more advanced civilization to bring spiritual enlightenment to Earth, where humanity is seen to be floundering in ignorance. The extraterrestrial message is usually channeled through a charismatic human leader, who then mobilizes a group around this New Age "revelation." The Encyclopedic Sourcebook of UFO Religions discusses the histories and beliefs of prominent UFO-based sects; looks at group dynamics and other sociological factors; and presents selections from the unusual literature of the various groups. This revealing and disturbing study shows that there is much more to the UFO phenomenon than simple curiosity about the possibility of life on other planets.