The past decade has witnessed an increase in the number of investor-State arbitrations. With the increase has been a widening of the range and deepening of the complexity of issues raised, addressed, and resolved in the cases. In recent years, novel procedural issues have surfaced. One of them is whether arbitral tribunals have the authority to adjudicate claims of multiple investors in a single proceeding, and if so, how they should conduct the arbitration. In 2011, the tribunal in Abaclat & Others v. Argentine Republic, constituted under the auspices of the International Centre for Settlement of Investment Disputes (ICSID), held that claims of more than one investor, in fact, multiple investors, are admissible and that the tribunal had jurisdiction over them. Since Abaclat, another tribunal has similarly held that collective claims could be heard under the ICSID framework.2 The issue of multiple investors is one that will likely not fade so it is fitting that the Abaclat decision be re-published in International Legal Materials to promote wider access to it.