Far from being simply a sequence of techniques, as practised in many countries osteopathy is an independent primary health care system based on principles applied through a manual practice: a unique profession that takes care of the whole person through the application of five models (biomechanical, neurological, respiratory-circulatory, metabolic, and behavioral). These conceptual models of the relationship between structure and function allow osteopaths to evaluate treatment with the aim of promoting health rather than curing disease. This book is intended as a manual for both students and osteopathic professionals interested in exploring the principles, objectives, origins and application of the five osteopathic models, from traditional concepts up to a modern vision, based on evidence and critical thinking. The selection criteria and rules for the application of each model, with their limitations and potential, are examined, to enable the reader to understand the rationale behind their use in a comprehensive, holistic and patient-centered practice.