Rational Emotive Behavior Therapy provides an introduction to the theory, history, research, and practice of this influential approach. Created in the 1950s by the coauthor, Albert Ellis, rational emotive behavior therapy (REBT) was the pioneering cognitive-behavioral therapy. In essence, REBT helps clients learn to challenge their own irrational thinking and develop the habit of thinking in beneficial and rational ways. This shift enables clients to behave more effectively and, ultimately, experience healthy emotions. REBT is based on the simple idea that it is not external circumstances that make a person happy or unhappy, but rather internal thoughts about events or self. Thinking, feeling, and behavior are seen as linked and influencing one another. Because changing one's thinking is usually the simplest tactic in a given situation, it tends to be the focus of therapy, along with the encouragement to adopt the humanistic core REBT philosophies of unconditional self-acceptance, unconditional other-acceptance, and unconditional life-acceptance. Ellis and Joffe Ellis present and explore this influential, practical, and compassionate approach, its theory, history, therapy process, primary change mechanisms, and the empirical basis for its effectiveness. They also examine developments that have refined the theory and expanded how it may be practiced. This essential primer, amply illustrated with case examples featuring diverse clients, is perfect for graduate students studying theories of therapy and counseling, as well as for seasoned practitioners interested in understanding how this approach has evolved and how it might be used in their practice.