Just Kids by Patti Smith is a story of two friends and how they helped one another achieve their dreams of success. Patti Smith is a musician, poet, and artist who comes of age in the 1960's. She befriends Robert Mapplethorpe who becomes her friend, partner, muse, protector, and supporter. Patti and Robert becomes part of the art and music scene in New York at the height of the sixties. They have connections with Jimi Hendrix, Jim Morrison, Janis Joplin, Bob Dylan, and Andy Warhol as well as many poets and writers of the day.

Just Kids tells of Patti and Robert's evolving relationship as they mature and find success in both the art and music worlds. Patti leaves her home in southern New Jersey to find success in New York City. What she finds is a hard existence where she lives on the street for a time even when she finds a job she can barely afford to buy food. She questions her reasons for being in the city until she meets Robert Mapplethorpe. He becomes her protector and takes her into his life. They challenge each other to grow creatively.

As they grow and mature, their relationship changes. In the beginning, Patti and Robert are lovers who want nothing more than one another. Patti soon learns that Robert is a homosexual who is ashamed of his feelings toward other men. He was raised Catholic and feels that what he feels is a sin. He tries to suppress these feelings for Patti, but they are part of who he is. In their innocence, they attempt to stay together and promise that they will always be there for one another.

Robert has always known that he is an artist and he lives and breathes art. Patti is in a constant search for who she is meant to be. The people she meets through her relationship with Robert and the creative world of New York in the 1960's try to guide her toward where they feel she should be. She attempts art, acting, writing and music. She is an exuberant personality and this inhibits her acting ability. Robert encourages her art and poets such as Allen Ginsberg and Gregory Corso encourage her writing. Patti begins to find success as a poet and musician and forms relationships with other men as Robert also embraces his homosexuality and starts forming relationships with men. Patti and Robert are living separate lives, but are always there for one another. Patti finds success first as Robert begins to delve into photography as a way to express his artistry. Patti forms a band and mixes poetry and rock and roll for an eclectic mix that finds a large following.

As the pair matures and finds lasting relationships, their own relationship suffers. Patti marries and has children. She moves away from New York to Detroit. Robert and his partner develop AIDS and Patti is drawn back to New York to offer her support to her lifelong friend. Just Kids tells of the bond between two people forged during an innocent time that changed both of their lives. When they met, they were young naïve children. Over time, they grew up into successful adults who together helped shape an entire artistic era.