Self-organized networks based on mobile devices (e.g., Mobile Ad Hoc Networks [MANET]) are becoming a practical platform for pervasive social networking. People, either familiar or strangers, communicate with each other via such a network for instant social activities. How to help mobile users to build up trust in pervasive social networking is becoming an important and interesting issue. Trust concerns not only security, but also privacy, as well as quality of social networking experiences. It relates to many properties that are essential for establishing a trust relationship in ephemeral and dynamically changed pervasive social environments. This chapter reviews the literature with regard to how to build up trust in pervasive social networking. The authors explore whether pervasive social networking is demanded, considering many existing popular Internet social networking services. Based on a need assessment survey, they propose a trust management framework that supports context-aware trust/reputation generation, trustworthy content recommendations, secure communications, unwanted traffic control, user privacy recommendations, and secure face-to-face pervasive social communications. Simulations, prototype implementation, and user experiments further prove the effectiveness of the proposed solutions.