Open Source Software (OSS) groups experience many benefits and challenges with respect to the core group's effectiveness. In order to capitalize on the benefits and minimize the challenges, OSS groups must learn not only on the individual level, but also on the group level. OSS groups learn by integrating individual contributions into the group's product and processes. This paper reports on the characteristics of the learning process in OSS groups. The study utilized an embedded single case study design that observed and analyzed group learning processes in the Apache Web server OSS project. The study used learning opportunity episodes (LOE) as the embedded unit of analysis and developed and utilized three content analytic schemes to describe the characteristics of the learning process and the factors affecting this process.