The Bulletin Board System (BBS), when it first appeared in the middle 1970s, was essentially “a personal computer, not necessarily an expensive one, running inexpensive BBS software, plugged into an ordinary telephone line via a small electronic device called modem” (Rheingold, 1993). The networked computers used to create these parallel worlds and facilitate communication between human beings constitute the technical foundations of computer-mediated communication (CMC) (Nancy, 1998). CMC systems link people around the world into public discussions. While CMC can exist solely between two people or between one person and an anonymous group, increasingly, virtual communities of many people are being formed. With advent of the Internet, the World Wide Web (WWW) brought more new technologies to the BBS. Thousands of BBSs sprang up across the world. Many turned out tremendously successful and evolved into lively virtual communities. These communities provided forums with increasing importance for individuals and groups that share a professional interest or share common activities. Online BBS communities now play an important role in information dissemination and knowledge collaboration on the Internet. On one hand, online forums enable people to disseminate information in an extremely efficient way without geographical restriction. On the other hand, the freedom also comes with uncertainty. Any information can be released and the content is almost beyond control, or even unreliable. To understand the content and quality of the information in BBSs, we would split the task into two subjects: one is to assess the information sources; another is to assess the information providers, people themselves in the virtual communities. Most BBSs are anonymous, because people usually use a pseudonym rather than their real name when registering. A user does not need to provide real personal information to the system, either. Thus, how to assess the trust of the users in a BBS community and attract more trustful and worthy users to participate in the activities of the community have become crucial topics to establish a successful community. Two subjects are important for establishing user trust in a BBS community: First, a BBS system must be able to identify a user and provide efficient security protection for each user and his/her privacy. Second, the value and the trustworthiness of a user should be assessed according to that user’s behavior and contribution to the community in comparison to peers.