Whether for bi-lateral or multi-lateral joint venturesor for public and private partnerships (PPP), control helps parties form strategicalliances and work together on a unique project while protecting their own identityand goals. Even though most researchers consider formal control such ascontracts, governance mechanisms, budgets, schedules, and other projectmanagement tools, few encompass informal or social control. This study takesinto account both types of control and aims to describe the evolution of formaland social control mechanisms in an international PPP project. An in depth casestudy of a concession project in a European airport was performed and includesall partners in this Euro-Canadian consortium. Results suggest that fromfrequent and repetitive interaction between partners emerges a social control thatprogressively takes more importance in the management of the project. This isnot to say that formal control mechanisms first put forward are forgotten butrather that they are the foundation of all inter-organizational collaboration.