Disputes may concern projects involving various jurisdictions, parties from several countries, represented by foreign counsel and submitted to arbitral tribunals from different legal traditions. In this context, the language of arbitration is important in order to avoid unduly burdensome arbitration procedures in terms of time and costs, and to safeguard against any due process concerns that may arise as a result. While parties often select the language of arbitration in their arbitration agreement, in roughly a quarter of all ICC Arbitrations, this will not be the case. In those instances, arbitral institutions and tribunals must have the requisite tools to ensure that the language of arbitration does not become a stumbling block or, worse, a potential source of annulment of an award. The present article explores the questions of the relevance of the language of arbitration, and how it is determined in ICC Arbitrations. In so doing, it will provide insight into the ICC cases in which arbitral tribunals will be required to determine the language and provide an analysis of the criteria most often relied upon in arbitral decisions on the language of arbitration.