Investigations of Melanesia's so-called cargo cults tend to concentrate on the circumstances under which millenarian contexts of belief, attitude, and value are generated. In themselves, though, contexts do not precipitate millenarian movements. Instead, as the millenarian history of the Yangoru Boiken, East Sepik Province, Papua New Guinea indicates, movements must be constructed from millenarian milieus, a process requiring that leaders not only generate attractive explanatory schemes but also present themselves as particularly privileged ideological sources. Success in this latter task, however, will be serendipitously configured by nonideological factors, especially historical and geocultural circumstances that help create a perception of regular and favored access to knowledge of Westerners and their wealth. These limiting contingencies must therefore be considered in any comprehensive attempt to understand the leadership, spatiotemporal patterning, and scale of Melanesian millenarian movements.