This paper sets out to prove that characters in Eugene O’Neill’s Long Day’s Journey into Night assert themselves, and in the process, disintegrate the family and disrupt social cohesion. It is based on the assumption that O’Neill’s characters in this play cannot attain the self without family and societal disintegration. It seems that self-fulfilment and family/social cohesion cannot be achieved simultaneously these characters tend to pay attention to one of these values at a time. Individual frustration precedes instability in the family and societal relationships. The theories adopted as appropriate tools for this paper are Psychoanalytical theory and Deconstruction. This choice is guided by the major preoccupation in the paper. Psychoanalysis helps in analyzing the psychical state of characters in the play before, during, and after the quest. Meanwhile, Deconstruction facilitates the examination of the indeterminacy of the characters’ quest for the self in O’Neill’s Long Day’s Journey into Night. One of O’Neill’s major concerns is human relationships, especially marriage, and the challenges that usually characterize these relationships. Characters’ quest to assert themselves while, intentionally or not, ignoring their family and social responsibilities leads to individualism and self-destruction. O’Neill advocates the harmonization of self questing with unity in the family and social cohesion if self-fulfilment will be achieved.