Rational emotive therapy was developed by Albert Ellis in the mid-1950s. Ellis proposed that people become unhappy and develop self-defeating habits because of unrealistic or faulty beliefs. In research reports from Ellis in 1979 and 1987 he introduced the model that most irrational beliefs originate from three core ideas, each one of which is unrealistic. These three core and unrealistic views include: 1) I must perform well to be approved of by others who are perceived significant; 2) you must treat me fairly—if not, then it is horrible and I cannot bear it; 3) conditions must be my way and if not I cannot stand to live in such a terrible and awful world. These irrational thoughts can lead to grief and needless suffering.

As a therapy, RET is active. The RET therapist strives to change irrational beliefs, challenge thinking, and promote rational self-talk, and various strategies are used to achieve these goals. These strategies may include: disputing irrational beliefs (the therapist points out how irrational it would be for a client to believe he or she had to be good at everything to be considered a worthwhile person), reframing (situations are viewed from a more positive angle), problem solving, role-playing, modeling , and the use of humor. The client may also be requested to complete certain exercises at home, and bibliotherapy (reading about the disorder) may also be used as components of RET.