Shared understandings are important for software development as they guide effective individual contribu- tions and coordination of the software development proc- ess. However, it is not clear if such understandings can be developed in highly distributed groups that do not regu- larly meet face-to-face. In this paper, we present the re- sults of a preliminary analysis of shared mental models within a Free/Libre Open Source Software (FLOSS) de- velopment team. We analyzed mental models using cogni- tive mapping and process analysis and compared the models of four developers from the Apache Lucene Java project. Our analysis suggests that there is a high level of sharing among core developers but the sharing is not complete, with some differences related to tenure and role in the project. Finally, we suggest directions for further research on shared mental models in FLOSS teams.