The practice of international arbitration continues to grow, and the parties involved have become increasingly diverse. The arbitrators, however, still look the same: they are almost uniformly older, white males. This article focuses on the lack of ethnic diversity among international arbitrators, as represented by the lack of diversity of nationality. The author uses a regional framework to analyze International Centre for Settlement of Investment Disputes (“ICSID”) arbitrator and party nationality data, dividing the globe into four regions: Anglo-Europe, Africa, Asia, and Latin America. The ICSID data show that arbitrators are overwhelmingly Anglo-European, despite the diverse nationalities of the parties involved in arbitrations. The author suggests that the consistent lack of ethnic diversity among arbitrators is rooted both in Anglo-Europeans’ historical influence in arbitration, and in the arbitrator appointment procedures, which make it difficult for newcomers to establish themselves in the field. As a solution, the author proposes a regional diversity requirement for the sole arbitrator or the presiding arbitrator of a tribunal: the decision-maker and the parties cannot be nationals of the same region. This requirement would increase demand for non-Anglo-European arbitrators. Further, it would make the composition of arbitral tribunals better reflect the diverse nationalities that use arbitral institutions and it would reduce perceptions of arbitrator bias.