Poole describes a case study of a young boy from the Bimin-Kuskusmin culture of Papua New Guinea who developed a fantasy of an unborn imaginary twin. The author summarizes his integration of psychoanalytic theory on preoedipal experience, structures, and processes, and hypothesizes that separation-individuation and disidentifying from the mother is traumatic for Melanesian boys. A long case study is presented of the boy's fantasy from the ages of two years nine months to three years seven months. The author discusses the fantasy in terms of a variety of projective, mirroring, and other intrapsychic functions and concludes that it served as an "enduring transitional phenomenon" in the boy's developmental struggles with his family.