In this paper we investigate group maintenance behavior in community-based Free/Libre Open Source Software (FLOSS) development teams. Adopting a sociolinguistic perspective, we conceptualize group maintenance behavior as interpersonal communication tactics-specifically, social presence and politeness tactics-that help maintain relationships among group members.Developer email messages were collected from two FLOSS projects with different development status and content-analyzed to identify frequently-used group maintenance tactics. We then compared the two projects on the group maintenance tactics used, finding differences that reflect changes in the project work practices. Our work contributes theoretically to FLOSS research and has practical implications for FLOSS practitioners.