How to create or support the coopetition between rival firms considering the risks of opportunism inherent in the coopetitive context? The role of go-between broadly answers this question. Few pieces of research have tackled the role of intermediary in the context of coopetition. The aim of this study is to understand the mechanisms between intermediaries and firms involved in coopetitive relationships. We conducted 58 structured interviews in 37 organizations in the aeronautical and aerospace engineering sector.