This paper is an analysis of online discussions in an Open Source Software (OSS) design community, the Python project. Developers of Python are geographically distributed and work online asynchronously. The objective of our study is to understand and to model the dynamics of the OSS design process that takes place in mailing list exchanges. We develop a method to study distant and asynchronous collaborative design activity based on an analysis of quoting practices. We analyze and visualize three aspects of the online dynamics: social, thematic temporal, and design. We show that roles emerge during discussions according to the involvement and the position of the participants in the discussions and how they influence participation in the design discussions. In our analysis of the thematic temporal dynamics of discussion, we examine how themes of discussion emerge, diverge, and are refined over time. To understand the design dynamics, we perform a content analysis of messages exchanged between developers to reveal how the online discussions reflect the “work flow” of the project: it provides us with a picture of the collaborative design process in the OSS community. These combined results clarify how knowledge and artefacts are elaborated in this epistemic, exploration-oriented, OSS community. Finally, we outline the need to automate of our method to extend our results. The proposed automation could have implications for both researchers and participants in OSS communities.