The present study was an exploratory investigation of a unique phenomenon: the traditional, Theravadin Buddhist meditation retreat. It is unique in the sense that such meditation retreats involve the constant practice of "concentration" and "insight" meditation techniques during every waking moment for periods of time up to 3 months. The following research questions derived from Buddhist sources and contemporary psychological theory and research, provided the major organizing framework of the study; (1) Are relationship factors, such as idealization, an important component of retreat experience? (2) In a Western, psychoanalytic sense, are the meditators characterized by a healthy sense of "narcissism" or self-love? (3) What is the nature of the meditators' self-concepts? (4) What are the effects of the meditation retreats on the participant's experience of self and world? All subjects were solicited, unpaid, volunteers recruited from the Insight Meditation Society (IMS) during the autumn and winter of 1979-80. The design of the study was naturalistic in the sense that it utilized the natural groupings of the IMS: the 3 month and 2 week meditation retreats. A total of 53 meditators completed the pre and post-retreat test packets: a sample of 20 subjects from the 3 month retreat and a pooled sample of 33 subjects from 3 different 2 week retreats. The self-administering test package included a Semantic Differential with 5 factor scales and 12 concepts, Knapp's Metaphor Scales (MS), and a Who-Are-You (WAY) test in addition to several less important measures. The data analysis was based on the interpretation of sample descriptive statistics, "Matched" T-tests, and analysis of covariance. As reflected by the WAY test, "Abstract" self-concepts predominated over "Role" and "Trait" self-descriptions, suggesting the meditators have an ideological commitment to the "anatta" (no-self) principle of Buddhism. Self-concepts were not significantly effected by either retreat experience. Comparison of the relative magnitude of the profile of semantic factor means for the concepts "Me" and "Your Meditation Instructor" documented that the relationship is an important factor in both types of meditation retreats. Both groups of meditators idealize their teachers, find them reliable and consistent, and experience them as emotionally rewarding. Among the 2 week sample, only, there is evidence that something akin to an "idealizing transference" (or perhaps a more general "positive transference") develops in relation to the teacher. Personality change among the meditators may be as much due to the relationship with the teacher as it is to the practice of meditation, per se. Judged in relation to 3 Western variables, derived from modern clinical theory, both samples appeared to have a healthy sense of "narcissism". These clinical variables seemed unaffected by the meditation retreats. However, important changes in the experience of self and world did occur among the 3 month sample. These results were consistent with Theravadin Buddhist theory. The self was perceived as more "non-reactive", suggesting an increased mastery of the "insight meditation" technique of "bare attention". The connotations of death changed, suggesting an increased appreciation of "anicca" (impermanence) and acceptance of the theory of reincarnation. The 3 month meditators come to reject a Western, romantic, interpersonal definition of love in favor of the Buddhist emphasis on an internally generated and maintained feeling state and stance of selfless, altruistic, "non-reactive", non-selective, compassion for the world. Finally, the 3 month retreat seemed to increase the participants' emotional detachment from and devaluation of Western attitudes concerning work and material strivings. Additional, but less important findings are reported in the body of the study.