In this overview of one of the most successful forms of psychotherapy -- Rational Emotive Behavior Therapy (REBT) -- its creator and chief advocate, Albert Ellis, explains at length the principles underlying this therapeutic approach and shows how beneficial it can be, not only for therapy but also as a basic philosophy of life. As the title indicates, REBT promotes an attitude of tolerance, an open-minded willingness to accept the frailties, less-than-ideal behaviors, and unique characteristics of both others and ourselves. Ellis persuasively demonstrates that lack of tolerance of our own imperfections can easily lead to emotional disturbances and unhappiness. And intolerance of others, which fails to account for the great diversity of human personalities and behaviors, can become a serious disruptive force in today's highly diverse, multicultural global society. To counter such negative tendencies, Ellis advocates the adoption and practice of three basic attitudes of tolerance: (1) Unconditional Self-Acceptance (USA); (2) Unconditional Other-Acceptance (UOA); and (3) Unconditional Life-Acceptance (ULA). He discusses the philosophical foundations of these principles and then devotes a number of chapters to comparing REBT to spiritual and religious philosophies. He points out the dangers of fanatical tendencies in religion while also showing how the basic principles of REBT are similar to some ancient religious philosophies such as Zen Buddhism and the Judeo-Christian Golden Rule. In addition, he criticizes certain secular philosophies for their extremism, including Fascism and Ayn Rand's Objectivism, and he also discusses the ramifications of applying REBT in the social, political, and economic sphere. In emphasizing how easy it is for all of us to think, feel, and act intolerantly, Ellis brilliantly shows that tolerance is a deliberate, rational choice that we can all make, both for the good of ourselves and for the good of the world.