Repeated signs of a large-scale rebellion on the South Pacifie island of Tanna (Vanuatu) appeared in 1941. Civil disobedience was expressed through reference to a prophetic figure namedJohn Frum. In order to repress this politico-religious movement, categorized later as a cargo cult in the anthropological literature, the British administration accumulated thousands of pages of surveillance notes, reports and commentaries. This article proposes an introduction to the existence of these documents known as the 'John Frum files', which were classified as confidential until the last few years. The presentation of this body of documentation follows Ann Stoler's injunction to study colonial archives not only as data sources but also as an ethnographie subject in its own right. An ethnographie overview of the John Frum files will contribute to recent debates among anthropologists about 'cargo cult archives' and how their colonial authors in Tanna and John Frum cultists were inextricably bound up with one another.