This thesis aims to establish whether there is any justification for regarding the alleged alien close encounter experience as a contemporary category of traditional religious experience. The development of the phenomenon is examined against the background of its historical context. Accounts of such meetings are methodically analysed, and content, structure, and symbolism are identified. This same analysis is applied to a range of experiences reported in traditional religious contexts to identify possible parallels and dissimilarities. In the light of this systematic comparative and phenomenological approach it ha become apparent that a unifying thread runs through the alleged alien encounter reports and the traditional religious contexts. Despite certain dissimilarities, it is shown that the content of these various experiences also exhibit a homogeneity: the stories conform in their type of setting; their sequence of events; the messages the individual receives; the individual's reaction to the events; and the long term effects of these events on the individual. The religious experiences selected for comparison are Rites of Passage; Shamanism; Medieval Otherwor1d Journeys; Marian Revelations; and Near-Death Experiences; all are respected and accepted expressions of religious sentiment. Given the acceptance of these experiences and the strong kinship with the close encounter claims, it would appear that there is justification for more regard to be accorded to the contemporary close encounter experience. Generally treated as the fantasies of attention-seeking individuals, this modem phenomenon apparently shares some of the same life-enhancing and transformative aspects of traditional religious experiences, directing the individual towards a more fulfilling and defined sense of self, and a more encompassing and compaSSionate view of the cosmos. The modem close encounter claimant shares with his fellow, more traditional, otherwor1d travellers a sense of purpose, and the belief that he belongs to something much greater than himself.