The book aims at analyzing the novels of the Jewish American novelist, Joseph Heller in the light of existentialism. Existentialism is taken to be a philosophical movement which foregrounds the sordid realities of human existence like alienation, boredom, futility, absurdity, Nothingness, anxiety, and anguish, through uncompromising subjectivism and decisionism.The root sense of 'ex-sistence' is 'standing out'. Man is a subject. He is 'a-being-in-the-world' and at the same time 'a-being-with-others-in-the-world'. Sartre calls these two states of being 'en-soi' and 'pour-soi'. Man's subjectivity ranges from pre-reflective cogito to rational consciousness. He exists even without being aware of this and gradually comes to find himself in a freedom of possibilities. When man becomes part of the world, he ceases to 'ex-sist' in the full sense. Also, without the world, he loses his selfhood. He therefore finds himself at the centre of a tension, and must survive in the face of opposing pressures. As a being-in-the-world, man is characterized by a fundamental openness or freedom. He realizes this freedom as a set of extreme possibilities, by dent of which he is able to do anything. The existent, in projecting himself, throws himself forward into his possibilities and plunges into action, for only in action does existence attain concreteness. But the problem of freedom is that it contains in itself the seeds of its own destruction. Freedom is itself not free. It is hedged about in innumerable ways. The limitations of freedom are collectively called facticity. Existence never escapes from the tension between possibility and facticity. In his ethical subjectivity the existent claims that moral judgments are fundamentally individualistic emotionally and intellectually. From this it follows that nothing could be called right or wrong, and no outside authority, agent or institution might be invoked for sanctions or prohibitions. But as man is also a being-with-others-in-the-world, and society has framed a code of ethics, man finds himself conditioned to be free, and so to choose. In choosing himself he alienates himself from the 'Other' and in choosing the 'Other' he becomes alienated from his own deepest being. In choosing himself, he assumes his personal individual responsibility for his action. But in the latter case, the 'Other' takes away the power of choice, and disburdens the individual of his responsibility. In this case, he may not suffer anxiety, but eventually he loses his selfhood and becomes an object in the world, or part of the crowd, and suffers inauthentic existence. Existence with others is to be judged authentic to the degree that it lets individuals be free to become the unique persons that they are. True community allows for true diversity. But in spite of finitude, alienation, and even sin or error, and crime, man quests for his true life. Thus existentialism analyses the human condition and drives one towards living authentically.The book discusses Joseph Heller's novels as Catch-22, Closing Time, Something Happened, Good as Gold, Picture This, Portrait of an Artist as an Old Man, and God Knows in the light of these Existential Concepts.