Managing trust is a problem of particular importance in peer-to-peer environments as one encounters frequently unknown agents. Existing methods for trust management based on reputation do however not scale as they rely on some form of central database or global knowledge to be maintained at each agent. In this paper we illustrate that the problem needs to be addressed at both the data management and the semantic, i.e. trust management, level and we devise a method of how trust assessments can be performed by using at both levels scalable peer-to-peer mechanisms. We expect that such methods are an important factor if fully decentralized peer-to-peer systems should become the platform for more serious applications than simple file exchange.