To generate a massive archive of data, one must often first convince a large number of scientists that they have more to gain by sharing their data than by retaining proprietary control over it. The production of “big data” is therefore often dependent on the production of what might be called “big communities,” or at least the production of communities of scientists who believe that “bigness” is valuable or inescapable. This paper explored the mutual production of data and community by tracing efforts to collect, archive, and distribute records of animal movements over the past century. It begins in the early twentieth century with the creation of the first centralized repositories for bird-banding data by natural history museums and government agencies, which sought to bring discipline to the field as individual banding projects proliferated. The scientists behind these coordinating efforts aimed both to organize data and to organize the ornithological community—or, more precisely, to organize the community by organizing data — at a time when the superiority of professionals over amateurs remained uncertain. The paper ends with Movebank, an online repository for animal movement data that was launched in 2009. Initially styled "MoveBank" in imitation of the genetics database GenBank, the repository aims to collect and disseminate movement data on many kinds of animals and all regions of the world, although these ambitions have yet to be fully realized. Like the twentieth-century data-organizational efforts that preceded it, the success of Movebank will depend on the articulation of a particular technical infrastructure with a particular form of scientific community.