We explore peer-to-peer discussions which took place in a UK-based diabetes 'Virtual Clinic' online community. In particular, we seek to understand the rhetorical nature and content of exchanges over a period of six months from the community's inception. Data were captured weekly and analysis based on thematic discourse analysis. Two key issues emerged regarding how the community shaped the nature of the discussion forum. First, the identity of the forum was established, and boundaries drawn about what was, and was not, acceptable. Second, participants sought to present themselves as reliable and authoritative sources of information. Internet discussion communities are shaped in important ways early on by the community of users, including how the character and focus of discussion is formed, and how both information and users can be constructed as authoritative and reliable.