This introduction presents an overview of the key concepts covered in the subsequent chapters of this book. The book provides essential information on generalized anxiety disorder (GAD) such as definitions, prevalence, course, comorbidity, and the overall burden it imposes. It also provides a brief overview of emotion-focused therapy (EFT) theory. The book focuses on emotion transformation model of GAD, based on the research projects run in the first author's lab. It also presents research-informed propositions about the qualities of the therapeutic relationship offered by the therapist that contribute to the client's sense of safety, emotion regulation, and corrective emotional experiences. The book also focuses on the strategies employed to access and differentiate the core emotional pain in the context of working with clients with GAD difficulties. It explains issues of timing and the strategic use of therapy in specific circumstances such as time-limited therapy.