Abstract. In this paper, we propose a Bayesian network-based trust model in peerto-peer networks. Since trust is multi-faceted, even in the same context, peers still need to develop differentiated trust in different aspects of other peers’ behaviors. The peer’s needs are different in different situations. Depending on the situation, a peer may need to consider its trust in a specific aspect of another peer’s capability or in a combination of multiple aspects. Bayesian networks provide a flexible method to represent differentiated trust and combine different aspects of trust.