Data Envelopment Analysis (DEA) has emerged as a powerful tool in the realm of performance assessment, efficiency measurement, and decision-making across various sectors. These proceedings include selected papers presented at DEA45, a conference organized by the Centre for Business Analytics in Practice at the University of Surrey in September 2024. DEA45 was convened not only as a platform for showcasing the latest developments in DEA, but also to commemorate the 45th Anniversary of the seminal paper by Charnes, Cooper, and Rhodes,1 which introduced DEA for the first time in 1978. As we reflect on the remarkable journey of DEA over the past four and a half decades, DEA45 provided an invaluable opportunity for scholars, practitioners, and enthusiasts to celebrate the enduring impact of Charnes, Cooper, and Rhodes’ pioneering work and to chart the future trajectory of DEA research and applications. In this comprehensive volume, we bring together a collection of 24 papers that delve into diverse aspects of DEA, showcasing its versatility and applicability in addressing real-world challenges. The chapters in this book span a wide spectrum of topics, ranging from methodological advancements to practical applications in different industries and contexts. Each chapter offers distinct perspectives, methodologies, and empirical discoveries, enriching the diverse landscape of DEA literature. This volume begins with a tribute to Prof. Jon A. Chilingerian, a pioneer in the field whose contributions have significantly shaped the landscape of DEA research. From foundational concepts to cutting-edge methodologies, these proceedings cover a breadth of topics, including inference in dynamic, nonparametric models of production, Bayesian approaches for bias correction, and applications in various sectors such as theatrical firms, ports, and thermal energy generation plants. Exploring the intersection of DEA with other analytical techniques, such as fuzzy logic, path-based models, and intuitionistic fuzzy models, we uncover new avenues for enhancing decision-making processes and gaining robust insights. Moreover, we examine the impact of DEA in diverse domains, including banking, education, healthcare, and environmental sustainability. In the face of the unprecedented challenges posed by events such as the COVID-19 pandemic, DEA provides valuable insights into evaluating and enhancing resource allocation and performance within regional health systems. Furthermore, this volume sheds light on the global economic landscape, offering comprehensive analyses of economic performance over time and space through the lens of DEA and the Malmquist index. As we navigate through the intricacies of efficiency measurement and performance evaluation, we also explore the practical implications of DEA in policy formulation and decision support. From identifying best practices in educational funding to informing policy decisions in public basic education and electric power transmission, DEA serves as an invaluable tool for informed decision-making and policy design. Lastly, we introduce DEA-Viz, a software tool designed to facilitate the visualization of DEA problems, enhancing the accessibility and usability of this powerful analytical framework. In assembling this collection of papers, we aim to provide researchers, practitioners, and policymakers with a comprehensive resource that not only showcases the state-of-the-art in DEA research but also inspires future advancements and applications. We hope that this volume serves as a catalyst for further exploration and innovation in the ever-evolving field of Data Envelopment Analysis. We extend our heartfelt gratitude to all the authors whose dedication, expertise, and scholarly contributions have made this volume possible. Additionally, we extend our sincere thanks to all the reviewers whose invaluable feedback and constructive critiques have enhanced the quality and rigor of each chapter. We would also like to express special thanks to Springer and Springer Production, especially Jialin Yan and Christian Rauscher, who supported the publication of this volume in the Springer series of Lecture Notes in Operational Research. Finally, it is essential to clarify that the responsibility for the content, accuracy, and interpretations presented in each chapter lies solely with the respective authors. As editors, we facilitate the compilation and organization of the material, but we do not assume any responsibility for errors, inaccuracies, or omissions that may be present within individual chapters. While every effort has been made to ensure the quality and integrity of the content, readers should exercise their judgment and discretion when interpreting and utilizing the information provided.