How can we account for the accomplishments of online collaborations? What motivates people to contribute to them? This exploratory study catalogues the features conducive to the success of such collaborations, focusing on the reduced costs of both individual contributions and the social organization of production, as well as the excessively large number of potential contributors attracted to focal collaborations. Research shows that participants’ motivations for collaboration vary across projects, involving a mixture of self-regarding and other-regarding motivations. I argue that when contributions originate among a heterogeneously and non-heroically motivated following, their vast quantity is conducive to project success despite a high percentage of free-ridership. The key challenge for such collaborations is not how to motivate the reluctant, but rather how to find enough people predisposed towards cooperation, engage them and match their abilities to project needs.