A Portrait of the Artist as a Young Man breaks new ground in literature by forgoing a conventional plot. Instead, the novel is structured around the evolving consciousness of its protagonist, Stephen Dedalus. A key theme throughout the book is Stephen's growing awareness of the world, which is explored in distinct ways across the novel’s five chapters. Stephen experiences various forms and levels of awareness, and Joyce uses an innovative “stream-of-consciousness” technique to illustrate Stephen’s thoughts and experiences.

Stephen's earliest awareness is expressed through his five senses, a motif introduced on the first page. Joyce details Stephen’s perception of his father’s face, the feeling of a wet bed, the “queer smell” of the oilsheet, and the comforting scent of his mother. He sings a song and listens to his mother play the piano.

From the beginning, Stephen perceives words as entities in their own right. When he attends Clongowes Wood College, he starts to grasp the meanings of words and realizes that a single word can carry multiple meanings. Stephen's sense of trouble is initially indistinct—he doesn’t fully understand the argument between Dante and Mr. Casey during Christmas dinner but senses the tension. He expects trouble when Father Dolan enters the classroom and threatens to “pandy” any “idle, lazy” boys. Later, he becomes aware that his father is facing some sort of difficulty, though its nature remains unclear to him.

Stephen’s awareness of the opposite sex emerges early in his life, although it doesn’t lead to action until the end of Chapter Two, when he meets a prostitute. This encounter is followed by his troubled awareness of sin. However, his creative consciousness is most significant. As the novel unfolds, Joyce’s language becomes more complex, mirroring Stephen’s growing maturity and understanding. Concurrently, Stephen becomes increasingly aware of his artistic destiny, culminating in his final chapter decision to fully commit to his art, regardless of how it impacts his life.

The central theme of the book is the growth of a young artist and his interactions with the society around him. The story opens with baby Stephen becoming aware of language and the world through his senses. Since the novel is largely autobiographical, it explores not only Stephen's development as a literary artist but also mirrors Joyce's own experiences. Joyce advocated for the concept of “art for art’s sake,” which is clearly reflected in A Portrait. He believed that art should not have a utilitarian purpose. In Joyce's view, an artist's duty was not to express political or religious views, nor to educate the public about societal issues. Instead, the artist should remain detached from societal matters and concentrate solely on their art.

For both Stephen and Joyce, mastering language to create art is its own reward. Stephen shows a particular sensitivity to words and the beauty of phrases, such as “a day of dappled seaborne clouds” and “Madam, I never eat muscatel grapes.” He is more captivated by the sound and suggestion of sentences than their literal meanings. This musical and evocative quality is evident in the villanelle (“Are you not weary of ardent ways …”) that Stephen writes near the end of the novel. Because of his artistic nature, Stephen feels increasingly alienated from society. He sees the artist’s role as an independent priesthood “of eternal imagination,” which ultimately distances him from the Catholic Church, political involvement, and typical Irish life.

Throughout the story, Stephen frequently notes his sense of being different and apart from his peers, siblings, and even friends. In the final pages of the novel, Stephen expresses his artistic manifesto in his diary: “I go to encounter for the millionth time the reality of experience and to forge in the smithy of my soul the uncreated conscience of my race.”

A Portrait of the Artist as a Young Man is not usually classified as a “coming of age” novel. Joyce aimed for the book to encompass a wider range, going beyond the limited timeframe—often just a school year or summer—typical of the “coming of age” genre. The novel covers approximately twenty years, following Stephen Dedalus from his early childhood through his college years. Despite this, the book features several traditional “coming of age” themes. These include Stephen's developing sense of self-identity and awareness of family dynamics, his growing understanding of adult societal norms, and later, his increased curiosity and awareness regarding sexual matters.

Religion, especially the doctrines of the Roman Catholic Church, is a key theme in the novel. Set in late nineteenth-century Ireland, the story depicts a time when religion played a pivotal role in everyday life. Stephen's initial contemplation of God arises early in Chapter One. As he looks over his name and address in his geography book, he reflects on his position in the world. This introspection leads him to consider the immensity of the universe and the idea of God: “It was very big to think about everything and everywhere. Only God could do that….” He also ponders the diverse names for God across different languages and God’s ability to understand them all: “But though there were different names for God in all the dif- ferent languages in the world and God understood what all the people who prayed said in their different languages, still God remained always the same God and God’s real name was God.”

The significance of religion in Ireland, alongside the conflict between religious and secular powers, becomes evident during a heated argument between Dante Riordan and John Casey at Christmas dinner in Chapter One. The debate centers on the Church's position regarding the Irish nationalist leader Charles Stuart Parnell. Parnell, a member of the British Parliament, advocated for Home Rule, seeking limited self-governance for Ireland. However, his involvement in a divorce scandal, due to an affair with a married woman, Kitty O’Shea, led the Catholic Church in Ireland to condemn him, resulting in his disgrace and eventual death. Dante supports the Church's denunciation of Parnell, arguing that the Irish must follow the bishops and priests, even if it means forgoing their independence. Mr. Casey, also a Catholic, strongly disagrees with the Church's actions in Parnell's case, asserting that the clergy should not meddle in politics and exclaiming, “We have had too much God in Ireland.” Simon Dedalus echoes this sentiment, lamenting that the Irish are “an unfortunate priestridden race…. A priestridden Godforsaken race!”

Although Stephen remains a silent witness during this argument, he soon begins to wrestle with religious issues himself. A large part of the novel delves into Stephen's relationship with his faith and his eventual renunciation of it. Even as he distances himself from church authority, his Jesuit education and the deeply rooted Roman Catholic viewpoint continue to influence his perspective.

In Chapter Four, an unnamed dean invites Stephen to consider the priesthood. While Stephen is tempted by the idea and imagines himself leading a religious life, he ultimately rejects the notion of becoming a priest. He cherishes his autonomy too much and feels he cannot align with any organization. Stephen realizes that his strength will come not from joining the priesthood but from committing to his solitary art, even if it means sacrificing his family, friends, nation, and God.

Sin, particularly Stephen's awareness of it as described by the Catholic Church, profoundly influences his perception of God and religion. Troubled by his own transgressions, such as masturbation and encounters with prostitutes, Stephen seeks forgiveness through confession. After confessing, he experiences a "consciousness of an invisible grace pervading and making light his limbs.... He had confessed and God had pardoned him. His soul was made fair and holy once more, holy and happy." To him, life seems straightforward and beautiful, with limitless opportunities ahead. Despite his efforts, Stephen grapples with maintaining this state of grace and eventually succumbs to sin once more.