This book gathers a selection of peer-reviewed papers presented at the International Conference on Operations Research (OR 2023), which was held at Universität Hamburg, Germany, August 29?September 1, 2023. More than 700 scientists, practitioners, and students from mathematics, computer science, business/economics, and related fields attended the conference and presented more than 500 papers in plenary presentations, parallel topic streams, as well as special award sessions. The book discusses classical mathematical optimization, statistics, and simulation techniques. These are complemented by computer science methods and by tools for processing data, designing and implementing information systems. The book also examines recent advances in information technology, which allow big data volumes to be processed and enable real-time predictive and prescriptive business analytics to drive decisions and actions. Lastly, it encompasses addressing problems modeled and treated while considering factors such as uncertainty, risk management, and behavioral issues.