This book contributes to the empirical understanding of how arbitrators make their decisions on the substance of commercial disputes arising from international construction projects. It is based on in-depth interviews with 28 international construction arbitrators and on the analysis of dozens of international construction arbitration awards. The combined experience of those who participated in the author’s research amounted to hundreds of international construction arbitrations (~ 300 cases) in addition to several hundred international commercial arbitrations. It presents the results of the first and largest research to be undertaken in this area, and it will be useful to arbitration practitioners and scholars and to the wider audience of dispute resolution students, practitioners, and theorists. In turn, the book examines to what extent international arbitrators apply the law as the substantive norm, providing an explanation for that, and then offers insights into whether arbitrators, in fact, lean towards commercial and transnational norms to construe the parties’ contract before discussing to what extent international arbitrators take into account fairness considerations to reach their decisions on the merits of the parties’ claims. The book also examines to what extent international arbitrators apply mandatory rules of foreign law. Lastly, it provides insight into the effect of arbitrators’ background characteristics on their decisions. Written for arbitration practitioners (arbitrators and legal counsel) and scholars, the book will be useful for both experienced arbitrators and those starting their arbitration career or studying for their arbitration qualification. It will also be useful for project professionals involved in contract management and dispute resolution.