A birth fantasy hitherto undescribed but commonly shared by adolescent girl members of a socioeconomically deprived New York community is reported. The fantasy involves the 'conception' and subsequent 'birth' of an amorphous mass (jelly baby) resulting from the vaginal penetration of a menstruating lesbian by the finger or tongue of her partner. The authors speculate on the meanings of the fantasy in light of infantile theories of conception and birth, including cloacal fantasies, oral impregnation, and denial of castration.