Free/Libre and Open Source Software (FLOSS) projects are a form of commons where individuals work collectively to produce software that is a public, rather than a private, good. The famous phrase “Tragedy of the Commons” describes a situation where a natural resource commons, such as a pasture, or a water supply, gets depleted because of overuse. The tragedy in FLOSS commons is distinctly different: It occurs when collective action ceases before a software product is produced or reaches its full potential. This paper builds on previous work about defining success in FLOSS projects by taking a collective action perspective. We first report the results of interviews with FLOSS developers regarding our ideas about success and failure in FLOSS projects. Building on those interviews and previous work, we then describe our criteria for defining success/tragedy in FLOSS commons. Finally, we discuss the results of a preliminary classification of nearly all projects hosted on Sourceforge.net as of August 2006.