The 20th anniversary edition of the Austrian Yearbook on International Arbitration is a collection of 39 articles on current issues and hot topics in arbitration. It provides a comprehensive overview of recent developments in the field. The yearbook features "The Vienna Propositions on Efficiency in Arbitration" which summarize the discussions held at the VAD World Café in 2025. This year's contributions address a variety of international developments and challenges, predominantly concentrated on the role of the arbitrator and the arbitration procedure, from authors around the globe. Among others the Yearbook contains forward looking keynote speeches by Cavinder Bull SC, Professor Stavros Brekoulakis and Roland Ziadé, articles addressing efficiency, diversity, technology and AI, procedural issues, enforcements and ISDS. Furthermore, the Yearbook covers specific regional developments, including those in Austria, the Balkans, China, Germany, Hungary and the United Kingdom. The contributions also include a report providing insights into the successful work of VIAC.