Summary.A shared paranoid belief system was identified among members of a sect-like group. The imagined "paranoid pseudocommunity" includes both persecutorial conspiracies and networks extending and supporting the group. Delusional hypotheses are frequently reorganized within this paradigm, as are accompanying verbal styles. A paranoid perceptual and cognitive style is maintained by leader influence, information-processing roles of members, and the dogmatic, insular, elitist, and antagonistic qualities of this encapsulated subculture.Paranoid delusions seldom find adherents beyond a minority of one. Diagnostic classification reflects this fact by identifying no clinical entity broader than a pranoid dyad 1. Occasionally, however, larger groups of a sect of cult-like nature are infused with the paranoid ideation of a dominant member. This study examines such a group, the "League of Geniuses" (pseud.), focusing on the relationship between the belief system and a social system that encourages, orders, and maintains it in a "cognitive subculture". Interviews were conducted with a dozen members and ex-members over a period of a decade, and there was a comprehensive review of documents, speeches, and other communications 2.