Originally developed by Vitór Frade, at the University of Porto, Tactical Periodization is a methodology - popularized by coaches such as José Mourinho and Andre Villas Boas - that trains soccer players through a logical process that focuses on four moments of the game. These four moments are: Offensive Organisation, the Transition from Defence to Attack, Defensive Organisation, and the Transition from Attack to Defence. Through Tactical Periodization, the aim is to develop players to rapidly alter their on-field behaviours according to the tactical context of the match, and what actually unfolds in front of them. In turn, every training exercise focuses on at least one of the four moments, and always the coach's tactical game model of how he wants his team to play. In doing so, football players prepare and learn how best to conquer the often unpredictable matches that they encounter competitively. This book is the English language translation of the acclaimed book Periodización Táctica by world-renowned coach and sports science specialist Xavier Tamarit. *Important Note: What is Tactical Periodization is the translation of an academic book that examines Tactical Periodization's underlying philosophies, methodologies, and application. It covers areas such as systemic thinking, football as a complex phenomenon, and how the 'sum is greater than its parts'; it does not contain practical how-tos or drills. Candidly, it is not an 'easy' book to read, and requires a certain level of effort and concentration by the reader. However, for those who stick with it, the book provides a rewarding and high value resource for the modern football coach who wishes to understand exactly how Tactical Periodization developed, what it means for the sport, and how it can influence his or her coaching. Summary sections have been added to each original chapter to offer additional insight.