The existence of on-line social networks that include person specific information creates interesting opportunities for various applications ranging from marketing to community organization. On the other hand, security and privacy concerns need to be addressed for creating such applications. Improving social network access control systems appears as the first step toward addressing the existing security and privacy concerns related to on-line social networks. To address some of the current limitations, we propose an extensible fine grained access control model based on semantic web tools. In addition, we propose authorization, admin and filtering policies that depend on trust relationships among various users, and are modeled using OWL and SWRL. Besides describing the model, we present the architecture of the framework in its support. Categories and Subject Descriptors D.4.6 [Security and Protection]: Access Controls; I.2.4 [Knowledge Representation]: Semantic Networks General Ter...