Some open source software collaborations are sustained over long periods of time and across several versions of a software product, while others become abandoned even before the first version of the product has been developed. In this study, we identify factors that might be responsible for one or the other of these collaborative trajectories. We examine 107,747 open source software projects hosted on Sourceforge.net in August 2006 using data available through the FLOSSmole Project. We employ Classification and Regression Tree modeling and Random Forests statistical approaches to begin to establish an understanding of how various project attributes, especially physical and community ones, contribute to project success or abandonment. We find that factors associated with success and abandonment differ for projects in the early stage of development (pre-first release) compared to projects that have had a first release, and that product utility, project vision, leadership, and group-size are associated with success in open source collaborations. We also find that successful open source projects exist across all types of software and not simply in areas associated with the open source “movement.” Other evidence suggests that Sourceforge.net may play an important role in “intellectual match-making.”