Öz:Aaron Beck and Albert Ellis are the founders and the most influential figures of the modern cognitive therapy. Almost 40 years have elapsed since the early work of Beck and Ellis in the late 1950s in cognitive approaches to treatment of emotional disorders. Both were reacting classical psychoanalysis in which they had been trained. The work of Ellis and Beck and also their successors and successors work's gave rise to "cognitive revolution" of the 1980s. The strength of cognitive therapy from its inception has been its emphasis on empirical backing. Cognitive therapy has been a most successful psychotherapeutic movement of recent years with highly prolific research literature and continuous development of the underlying theory. In this review article brief history of cognitive therapy and basic theory of cognitive therapy were presented. Also partly clinical applications of the theory were explained.