[Summary] This book provides a comprehensive guide to Internal Family Systems (IFS) therapy, a trauma-informed approach to mental health treatment. This manual, written for therapists, outlines the core principles of IFS, which views the mind as a system of interacting parts, including protective parts, injured parts, and a core Self. It details the IFS model of the mind, explains how to assess and diagnose using IFS, and provides a step-by-step approach to working with clients, including how to identify and work with protective parts, unburden injured parts, and access the Self. The manual also explores common challenges therapists face in working with protectors and discusses the application of IFS to various mental health conditions, including trauma, anxiety, depression, and addiction. Finally, it offers guidance for applying IFS to specific populations, such as children, adolescents, and couples.