User’s privacy concerns represent one of the most serious obstacles to the wide adoption of mobile social software applications. In this paper, we introduce a conceptual model which tackles the problem from the perspective of trade-off between privacy and trust, where the user takes the decision with minimal privacy loss. To support the user decision, we introduce the Mobile Access Control List (Macl), a privacy management mechanism which takes into account the user attitude towards mobile sharing, his communication history and social network relationships.