A Portrait of the Artist as a Young Man is a story about the formation of a person, a bildungsroman. We follow step by step, from childhood to youth, the development of Stephen Dedalus as he grows up in County Kildare, Ireland. His father Simon Dedalus is a moderate. Dante, his aunt, is devoutly Catholic, while Uncle Charles is an Irish nationalist. Stephen sees everything with a child's simplistic view.

Stephen is soon sent into "exile", as his family decides he should study at Clongowes Wood College, a Jesuit school for boys. Here the young Stephen finds it hard to integrate. He doesn't take part in games with the other children. The older boys tease and bully him and treat him as an outsider. He often retreats into his thoughts, trying to sort out who he is. He is misunderstood, and experiences unjust punishment when he is caught not working in class; Father Dolan, the prefect of studies, lashes his hands, even though he had previously been excused by Father Arnall as he had broken his glasses. Stephen bravely goes to the Rector to report Father Dolan's unfair treatment. A kind man, Rector Conmee offers him justice. As Stephen emerges from the rector's office, all the boys cheer for him. He is recognized as a hero but remains isolated from the rest, continuing his self-imposed "exile".

Rejoining his family at Christmas is a happy time for Stephen. He associates this with a train coming out of a tunnel. He hates Clongowes.

Stephen goes on a short trip to Cork with his father. A Corkonian, his father embarrasses him with his long talks, drinking and flirting at the local pubs. The city reminds Stephen's father of his youth. His son cannot understand his feelings and attitude. He feels older and wiser than his father. Nonetheless, he is young and begins to be consumed by his awakening sexuality.

As his family's finances decay, Stephen is sent off to another Jesuit school called Belvedere, in Dublin. Here he interacts more with his peers, but always remains serious. He wins the prize for essays, and the prize money gives him the opportunity to provide for his family and live in a certain luxury, for a short time.

It is during this period of personal unrest that he discovers Dublin's brothel quarter and becomes involved with prostitutes. These encounters, which clash with his deeply-held Catholic faith, make him feel guilty and moody. He is still haunted by his first relationship with a girl named Eileen, with whom he experienced a pure, platonic love.

Stephen constantly struggles to determine his identity within his complex mind. The development of Stephen's consciousness in A Portrait of the Artist as a Young Man is particularly interesting because, insofar as Stephen is a portrait of Joyce himself, his story gives us insight into the development of a literary genius. Stephen's experiences hint at the influences that transformed Joyce himself into the great writer he is considered today.

As school days pass he remains alienated from his family. Despite his religious beliefs, he realizes that lust is taking hold of him as he struggles with worldly pleasures and sin. Stephen searches for an escape from the discord and incompetence around as well as the tumult within him. He is filled with regret as he reflects on his many sins of the flesh. It is the moment when he hears a priest, Father Arnall, speak of hell. The description of hell terrifies him, and he searches for a chapel where he can confess his wrongs. On his way home his spirits lift as he resolves to discipline himself.

Filled with joy he follows every act of devotion to God, determined not to fall again. However, after a short time his allegiance to the Catholic faith begins to fade.

Stephen pursues his studies at university. Here he becomes socially disengaged. He retreats further into himself, writing and studying literature. Finally, Stephen comes to the conclusion that he must refuse the ideologies around him. He asks his father's blessing and continues on the path he has chosen for himself – leaving Ireland to become an artist.