Aaron T. Beck, M.D., is an American psychiatrist and a professor emeritus in the department of psychiatry at the University of Pennsylvania. He is widely regarded as the father of cognitive therapy, and his pioneering theories are widely used in the treatment of clinical depression. Beck also developed self-report measures of depression and anxiety including the Beck Depression Inventory (BDI), the Beck Hopelessness Scale, the Beck Scale for Suicidal Ideation (BSS), the Beck Anxiety Inventory (BAI), and the Beck Youth Inventories. He is the President Emeritus of the Beck Institute for Cognitive Behavior Therapy and the Honorary President of the Academy of Cognitive Therapy, which certifies qualified cognitive therapists.
Albert Ellis, PhD (1913-2007) developed Rational Emotive Behavior Therapy in 1955. His most popular books include A Guide to Rational Living, The Practice of Rational Emotive Behavior Therapy, and Overcoming Destructive Beliefs, Feelings, and Behaviors.