Fifth in the series of Great Religious Festivals this fits into a category of folk material as well as religion -- and not into holidays as familiar connotation of Halloween might suggest. The authors approach the subject as anthropologists, and review the solemn religious significance of the three day span- Halloween, All Saints' Day and All Souls Day, tracing the sources of observance back to pagan mysteries. It seems of Celtic origin, though there are similarities in Egyptian, Greek and Roman legend. The addition of witches, goblins and fairies to the general acceptance of the prevalence of spirits of the dead show in the Celtic Samhain (Scotland, Norway, Ireland), while Protestant Europe had an additional association as the date on which Martin Luther posted his famous theses. The material expanded from Robert Burns' sources explains many survivals in the games we associate with Halloween; while the use of Jack o'Lanterns is given an Irish source. The history of witchcraft, of the identification of cats with witches, is explored from medieval times to the 17th century and the brief terror in Salem. Some anecdotal material relieves the scholarly approach.