Human beings in diverse times and places have conceived of an other world (or worlds) existing in parallel with the world of the living and involved in a variety of interchanges with it. Such other worlds have been variously identified with the abode of the dead, of animals, gods, spirits or demons or with the liminal phases of ritual (described by Turner and others), when everyday categories and norms are suspended and where hybrid and metamorphic beings emerge to participate in the performative re-making of reality. Such instances of passage between worlds have often been associated with moments of crisis or transformation, whether in the life of an individual (e.g. the transition form youth to adulthood) or of society as a whole, as in culturally demarcated occasions when spirits or the returning dead are allowed to roam freely among the living. Participants are invited to consider what it would mean to consider such multiple worlds and the relationships between them not simply as sets of culturally bounded beliefs but as legitimate objects of anthropological inquiry. What challenges does a conception of reality as doubled or multiple pose to our familiar protocols of description and analysis? Does the anthropological exploration of other worlds have anything to learn from Western philosophical concepts such as the 'invisible' (Merleau-Ponty), the 'Imaginary' (Lacan) or the 'virtual' (Bergson, Deleuze)? Might the ethnographic and comparative study of interactions between multiple worlds offer a unique and valuable resource for understanding and responding imaginatively to contemporary crises and transformations?