Cognitive therapy (CT) refers to a family of interventions and a general scientific approach to psychological disorders. This family has evolved from a specific treatment model into a scientific approach that incorporates a wide variety of disorder-specific interventions and treatment techniques. The goal of this article is to describe the scientific approach of CT, review the efficacy and validity of the CT model, and exemplify important differences and commonalities of the CT approaches based on two specific disorders, posttraumatic stress disorder and health anxiety.