We present an empirical analysis of a web forum in which followers of a health-related community exchange information and opinions in order to pass on and develop relevant knowledge. We analyzed how knowledge construction takes place in such a community that represents an outsider position which is not accepted by majority society. For this purpose we applied the Community of Practice (CoP) concept as a guideline for our analysis and found that many well-known activities of CoPs were true of the Urkost community. The social network analysis findings also supported interpreting this community as a CoP. But we found as well that this community had a variety of structural characteristics that the CoP literature deals with insufficiently. We identified the structure of goals, roles, and communication as relevant features that are typical of this outsider CoP. For example, the attitude of the core members towards people of a ‘different faith’ was characterized by strong hostility and rejection. These features provided an effective basis for the development and maintenance of a shared identity in the community. Our findings are discussed against the background of the necessity for further development of the CoP concept.