Pilgrimage involves movement of people, either as individuals or as members of a group, in search of the sacred. Spontaneous behaviour, miraculous events, and/or ecstatic visions of individual pilgrims have often resulted in complexity in ritual, meaning, and movement. Pilgrimages may start with individual ecstatic visions, unusual strange unworldly experiences, which are the experiences of “ordinary” people, certainly not of priests or politicians. Often they are uniquely human experiences which embarrass ecclesiastical authorities. As a pilgrimage tradition evolves, sacred sites may become formalized in organized socio-political systems with economic overtone. Even in these structured situations, individual people may still have powerful individual experiences. Eventually a pilgrimage tradition may be taken over by religious and political authorities, lose spontaneity, and become frozen in time. But even in these situations, in which large numbers of people may gather, there is a tremendous amount of “primal” energy in which innovations and visions may be evoked. Using case studies from pilgrimages around the world, the volume explores the ways many of these traditions have started and evolved. A common perspective is that of self-organization of complex structures in space and time. The variety of pilgrimage described in the book is remarkable. The subcontinent of India is the location of many sites such as the temples to the nine planets in Tamil Nadu, the pilgrimage circuits of Varanasi, early Buddhist pilgrimages in Sanchi and Bodh-Gaya, the great ruined city of Vijayanagara, those associated with the Ramayana, and the death ceremonies at Gaya. Beyond India, the self-organization and stability of pilgrimage systems are analysed for pilgrimages in Nepal (Kathmandu), Japan, Mexico, the Caribbean, Peru, Norway, and the US.