In an ever-changing professional landscape, mastery of selection tests has become an indispensable asset for candidates at all levels—A, B, and C. This comprehensive guide is designed to prepare aspirants for various selection tests, whether administered by institutions such as Hudson, Travailler.be (formerly Selor) in Belgium, the Civil Service and management centers in France, the Civil Service Commission in the United States, or the Australian Public Service Commission. The first section of the book focuses on reasoning tests, including numerical and verbal reasoning. It offers exercises developed in line with the test standards for 2025-2026 and provides detailed solutions, advanced calculation techniques, and essential tips for success. The second section delves into behavioral skills tests, specifically case processing, situational judgment, and in-tray exercises. This section features exercises, solutions, and strategies specific to each type of test, facilitating optimal preparation. The final section is devoted to oral interviews and utilizes the S.T.A.R method to prepare candidates for a variety of questions and case studies that may be presented to them. Beyond its thoroughness and meticulous structure, this book offers significant added value by including supplementary online resources. Access to a specialized website where selection test experts are available for coaching is provided, along with an online training platform offering a wide range of exercises that align with the concepts of recent actual selection tests. Whether you are a prospective candidate or an individual interested in understanding the mechanics of these tests, this book aims to serve as an invaluable resource. It emphasizes the importance of a bifaceted preparation approach that includes both theoretical comprehension and practical application, and offers additional tools to maximize your likelihood of success.