Sentimental Education is a novel set in France around the time of the creation of the Second French Republic in 1848. The Second Republic was created after the overthrow of the French monarchy. The main character of the book, Frederic Moreau, is a young Frenchman from a town called Nogent. He finds himself with a small inheritance and decides to pursue his education in Paris. He encounters an old friend there, Charles Desclauries, and meets a younger couple, Jacques and Marie Arnoux, on the ship to Paris. Frederic instantly falls for Marie. He and Charles attempt to enter high society and also associate with some young Parisians interested in bringing socialism and democracy to France. They meet Hussonnet, Senecal, Martinon, and Dussardier through these interests.

The first part of the book is built around Frederic's various plots to get closer to Marie Arnoux and make her his mistress. He cultivates a friendship with Jacques in order to accomplish his goal. During this time, Frederic engages in social climbing, meeting with some of the Parisian elite, such as Monsieur and Madame Dambreuse. He discovers that Jacques Arnoux is is having an affair with a woman named Rosanette. He is able to spend some time with Marie, but he has trouble getting as close to her as he would like. Jacques runs an art magazine and is constantly taking Frederic out to upper class social gatherings, which Frederic is using to promote his own reputation. Eventually, however, Frederic finds his inheritance dwindling and must return to Nogent.

Frederic spends several months in Nogent until he inherits vast sums of money from his uncle, Barthelemy. He returns to Paris in triumph and lives on his inheritance; he takes his place in high society and seeks out a mistress to increase his prominence. He continues to pursue Marie, and exposes Jacques's affair to her.

Frederic is constantly asked for loans and donations but refuses to help his friends' causes. Instead, he grows closer to the Arnoux's, but when he makes a move on Marie, she rejects him. He considers marrying Louise, the daughter of Monsieur Roque, a rich inhabitant of Nogent. While in Nogent, Charles begins a book-long attempt to usurp Frederic's life.

Frederic also has a falling out with Cisy and fights a duel against him that has little consequence. He pursues an affair with Rosanette and puts off marrying Louise. The revolution against King Philippe is successful, but the revolutionary forces fragment and fight one another. Rosanette and Frederic pursue their relationship outside of Paris, but he meets Marie again and confesses his love for her. To further complicate matter, he also decides to pursue a relationship with Madame Dambreuse. Rosanette and Frederic have a child, who dies. Rosanette and Madame Dambreuse push Jacques into bankruptcy. Frederic attempts to save Marie by giving Jacques money, but fails. He ends his relationships with Rosanette and Madame Dambreuse, and finds that Louise has married Charles. Years pass and Marie visits him at home. They confess their love for one another, but when Frederic sees her white hair, he immediately loses interest. Frederic is left with no lover at all.