The popularity and longevity of international arbitration depends heavily on the quality of arbitral awards, the arbitral process, and the tribunals appointed by practitioners and institutions. In this article, the authors argue that practitioners and institutions need to consider a more diverse range of candidates for arbitrator appointments, to enlarge and diversify the pool of arbitrators. Not only does diversity make sense from an ethical standpoint, but research has also shown that increased cognitive diversity is required to reduce the risk of biased decision making and improve the quality of awards. More cognitively diverse arbitral tribunals are therefore necessary to preserve the continued legitimacy and success of international arbitration.