In a collaboration-oriented Web community, users do not necessarily know the other participants. There can be thousands of members in such a community, so a new user may not recognize any individuals at the beginning. For example, in Wikipedia the outcome of collaboration is often displayed anonymously (or at least the user’s individual share is not emphasized), so the process of becoming acquainted with other users takes time. It is obvious that there are also social bonds and interpersonal relations within the Wikipedia community, but the relation between the user and the whole socio-technical system is more crucial.a I call this relation the User-System-Relation (USR). In mediated voluntary-based collaboration the user’s trust in the fairness and functionality of the socio-technical system is the precondition for a successful co-project. Various things affect the USR. I will explicate these factors in the case of Finnish Wikipedia and draw wider conclusions about the relationship of trust in mediated collaboration communities. If the user sees benefits in participating and does not question the expressed goals of a socio-technical system, her motivation, commitment and initiative become deeper. In this way he or she can consider becoming intensely committed to the project.