The principle of good faith is an often-invoked principle. In international arbitration, it is invoked among others in matters relating to the execution of the contract, the interpretation of the arbitration agreement or the conduct of the arbitral proceedings. This article gives an overview of different applications of the ‘good faith’ principle and shows how arbitral tribunals have applied the principle under both civil law and common law. This article does not propose a singular definition but rather descriptively lays out the various approaches arbitral tribunals have taken, with a particular focus on ICC disputes.