The primary theme of The Zoo Story revolves around absurdity and reality. At the play's outset, Jerry starts a conversation with Peter, selecting familiar topics like family and career to engage him. However, Jerry quickly begins to introduce bizarre remarks and questions into what initially seems like a typical conversation between two strangers getting acquainted. This becomes evident when Jerry, presuming Peter dislikes his daughters' cats, inquires if Peter's birds are sick. Peter responds that he doesn't think so, to which Jerry says:

"That's too bad. If they did you could set them loose in the house and the cats could eat them and die, maybe." These irrational and absurd moments in the play start to unsettle Peter's sense of reality and place. Yet, Jerry swiftly balances these instances with genuinely pleasant, benign remarks and captivating stories to keep Peter's attention. Throughout the play, as Jerry continues to share his tales, he carefully steers the conversation, manipulating Peter. By the conclusion, Jerry has distorted Peter's sense of reality to such an extent that Peter engages in a physical confrontation over what he perceives as "his" park bench, and in an attempt at self-defense, inadvertently assists Jerry in his own death. The stark reality of the events then hits Peter, prompting him to flee, exclaiming "Oh my God!"

In The Zoo Story, the theme of alienation and loneliness is portrayed as a fundamental aspect of the human experience, driving Jerry's actions throughout the play. From the moment Jerry enters Peter's life, it is apparent that he struggles with basic social interactions. Instead of a polite greeting like "Hello, may I sit down," Jerry's initial words are: "I've been to the zoo. I said, I've been to the zoo. MISTER, I'VE BEEN TO THE ZOO!" As Jerry shares his stories, Peter discovers that Jerry lost both parents at age ten and afterwards lived with his aunt, who passed away on the day of his high school graduation. Jerry also makes candid remarks about the boarding house where he resides and its other occupants, who resemble a makeshift family to him, despite his lack of real connection with them. He even includes these individuals in his nightly prayers. Albee quickly establishes Jerry's isolation from society and gradually reveals more about his life to the audience. The profound loneliness Jerry feels ultimately leads him to orchestrate his own death with Peter's unwitting assistance at the play's conclusion. In his final moments, Jerry finds peace and tells Peter: "I came unto you and you have comforted me. Dear Peter."

A key theme in The Zoo Story is the disparity between wealth and poverty and the misconceptions that arise between different social and economic classes. This theme is intricately linked to alienation and loneliness, as Albee suggests that the pressures of class are the root of Jerry's distress. The topic of class is introduced early in the play when Jerry questions Peter about his family and career, then provocatively asks: "Say, what's the dividing line between upper-middle-middle class and lower-upper-middle class?" Clearly, Jerry is not part of these classes, and he acknowledges his own sarcasm. However, Jerry's assumptions about Peter's life are surprisingly accurate, while Peter finds Jerry's existence entirely unfamiliar.

The Zoo Story is an intensely harrowing expression of estrangement in American society. The lack of communication between Jerry and his landlady’s vicious dog is merely an analogy for the hostility among living beings in a world in which alienation and lack of sympathy are deep-seated psychological conditions. The story of the dog leads to Jerry’s zoo story, but the roundabout, digressionary mode of relation...