Mystery cults are one of the most intriguing areas of Greek and Roman religion. In the nocturnal mysteries at Eleusis, participants dramatically re-enacted the story of Demeter's loss and recovery of her daughter Persephone; in Bacchic cult, bands of women ran wild in the Greek countryside to honour Dionysus; in the mysteries of Mithras, men came to understand the nature of the universe and their place within it through frightening initiation ceremonies and astrological teachings. These cults were an important part of life in the ancient Mediterranean world, but their actual practices were shrouded in secrecy, and much of what they were about has remained unclear until now. The earliest modern works on mystery cults emphasized their perceived relationship with Christianity, as both were concerned with hopes for the afterlife. More recent work has tended to follow this interest in doctrines rather than practices. But it is what participants did, and what they actually experienced, that should be central to our understanding. This is the first book to describe and explain all the major mystery cults of the ancient world, cult by cult, reconstructing the rituals and exploring their origins. It makes plentiful use of artistic and archaeological evidence, as well as ancient literature and epigraphy. Greek painted pottery, Roman frescoes, inscribed gold tablets from Greek and South Italian tombs and the excavated sites of ancient religious sanctuaries all contribute to our understanding of ancient mystery cults. Making use of the most recent work on these cults, the book is also informed by crucial current work on the anthropology and cognitive science of religion. Richly illustrated and clearly written, it is a significant contribution to the study of these cults, but it is also accessible to a general readership. More than any other book on ancient religion, it allows the reader to understand what it was like to participate in these life-transforming religious events.