Ellis was born in Pittsburgh, Pennsylvania and received his Ph.D. in psychology from Columbia University. He taught for several years at Rutgers and then entered private practice in 1950.
He is best known for the development of Rational-Emotive Therapy (RET), which contradicts the Freudian view of mental illness and states emotions are a derivative of our thought processes. The ABC's of emotion argue that an Activating event in a person's life result in a Belief about that event. This Belief, in turn, results in an emotional Consequence. According to Ellis, irrational beliefs about life events cause irrational emotions, and conversely, rational beliefs result in ration emotions. Treatment with RET involves the recognition of irrational beliefs and t6he replacement of this faulty system with a healthy rational belief about the events and the world.