Information mediation is one of the major approaches to solve interoperability problems related to heterogeneous information integration. This paper first discusses the concept of information mediation and typical mediation architecture. Two major mediation research projects, TSIMMIS and MIX, and their limitations, are discussed. Meta-model, a way for exchanging meta-data, is then introduced for the purpose of improving information mediation. Finally, a meta-model based mediation approach is proposed.