In 1968 Chabrol began working with film producer André Génovès and started to make more critically acclaimed films that would later be considered his "Golden Era". Most of these films revolved around themes of bourgeois characters and a murder is almost always part of the plot. Unlike his earlier films, most of these films centered around middle aged people. Chabrol often worked with the same people during this period including actors Audran and Michel Bouquet, cinematographer Jean Rabier, editor Jacques Gaillard, sound technician Guy Chichignoud, composer Pierre Jansen, set designer Guy Littaye, as well as producer Génovés and co-writer Paul Gégauff.
In 1968 Chabrol made Les Biches, one of his most acclaimed works. The film stars Stéphane Audran as the dominant and bisexual Frédérique, who finds a young protege in the bisexual Why (Jacqueline Sassard), until they both become the lover of a young architect named Paul (Jean-Louis Trintignant). Why ends up killing Frédérique, but it is unclear whether she murdered her cheating lover or the person that her lover was cheating with. The film received critical praise and was a box office hit. Chabrol followed this with a similar film The Unfaithful Wife (La Femme infidèle), in which a husband named Charles murders the lover of his cheating wife. It was later remade in 2002 by director Adrian Lyne. Chabrol finished the decade with This Man Must Die (Que la bête meure) in 1969. Based on an original story by Cecil Day-Lewis, in the film Charles (Michel Duchaussoy) plots to kill Paul (Jean Yanne) after Paul killed Charles' son in a hit and run car accident. However the film's ending is left intentionally ambiguous, and Chabrol has stated that "you'll never see a Charles kill a Paul. Never." The film was especially praised for its landscape cinematography.