Carnal Knowledge is a 1971 American comedy-drama film directed by Mike Nichols and written by Jules Feiffer. It stars Jack Nicholson, Candice Bergen, Art Garfunkel, and Ann-Margret, with Rita Moreno and Cynthia O'Neal.

In 1946, Amherst College student Sandy meets a Smith College student named Susan at an on-campus event and they begin dating. Although they enjoy each other's company, Susan is reluctant to enter into a physical relationship. Unbeknownst to Sandy, Susan is also pursued by Sandy's aggressive, womanizing roommate Jonathan, and they eventually have sex. Jonathan tries to persuade Susan not to have sex with Sandy, but after some delays, Susan does sleep with him. Jonathan pressures Susan to break up with Sandy; then breaks up with her as well.

In 1961, Sandy is married to Susan, while Jonathan still searches for his "perfect woman". Jonathan begins a relationship with Bobbie, a beautiful but shallow woman, but he eventually grows bored with her. Bobbie leaves her job at Jonathan's suggestion. She then becomes depressed, spending long hours doing nothing but sleeping in the apartment she shares with Jonathan. The relationship deteriorates. Jonathan berates Bobbie for not cleaning up the apartment while he is out working all day at a nine-to-five job. He claims that he does not understand why break-ups always have to end with "poison".

Sandy's relationship with Susan is faring no better. Sandy is dissatisfied and bored with the physical part of their relationship, even though he and Susan "do all the right things". He relates how they are "patient with each other" and concludes with a statement that perhaps sex is not "meant to be enjoyable with the person you love".

Sandy begins dating Cindy. Sandy, Cindy, Jonathan, and Bobbie find themselves together at Jonathan's apartment, where Sandy complains privately to Jonathan about his sex life with Cindy. Jonathan suggests to Sandy that they trade partners, to "liven things up a bit". Sandy goes to the bedroom looking for Bobbie. Cindy dances with Jonathan and reprimands him for attempting to bed her with Sandy nearby, but indicates she is open to seeing him on his own, saying he should contact her at a more appropriate time. In the meantime, upset by an earlier fight with Jonathan about her desire to get married, Bobbie has attempted suicide. She is found by Sandy, who calls the hospital to have her taken to intensive care.

In 1970, Jonathan presents a slideshow entitled "Ballbusters on Parade" to Sandy and Sandy's 18-year-old girlfriend, Jennifer. The slideshow consists of pictures of Jonathan's various loves throughout his life. He skips awkwardly over a slide of Susan, but not before Sandy notices. He also shows an image of Bobbie, saying they are divorced and have one child together, and he is paying her alimony. Jennifer and Sandy leave wordlessly. Some time later, Jonathan and Sandy walk down Park Avenue and discuss their lives.

Jonathan solicits a prostitute named Louise, and they go through a ritual dialogue about male–female relationships which is apparently a script written by Jonathan. At the end, Louise recites a monologue (again scripted by Jonathan) praising his power and "perfection", which apparently has become the only way Jonathan can now get an erection.

The script was originally written as a play. Jules Feiffer sent it to Mike Nichols, who thought it would work better as a film. The script contains numerous curse words, some of which were rarely heard on the screen before this time. Feiffer's play would eventually be staged for the first time in 1988 in Pasadena, California, and Dallas, Texas.