- The Delicate Delinquent was filmed from September 5-October 12, 1956 and is based upon a script entitled Damon and Pythias. Darren McGavin stepped in to fill the role of a police officer that was originally written for Martin. Although the credits show a copyright date of 1956, the film was released the following year, a common practice in Hollywood.
- Lewis, who also produced the film, played a 'juvenile', although he was 30 years old at the time.
- The romantic interest in the film was provided mainly by actress Martha Hyer, who married Hal Wallis in 1966, the producer of the Dean Martin/Jerry Lewis films. Hyer's fancy dresses in the film were designed by longtime Paramount costumer designer Edith Head.
- Comedian/impressionist Frank Gorshin made a rare dramatic appearance as a gang member in the film.
When Mike tries to make friends with Sidney, however, the lonely janitor questions the policeman's motives, but accepts his dinner invitation when Mike tells him he has a twenty-one inch television. Back at the police station, Riley orders Mike to work with Martha Henshaw, a city council aide sent to their precinct to investigate the juvenile crime problem. When Martha asks to meet a juvenile delinquent, Mike tells the wealthy socialite to go out and find one herself, and, in turn, Martha finds Sidney. When the three meet at the policeman's apartment for dinner, Mike and Martha agree to pool their efforts to help the young man, but Sidney quickly leaves when the two reformers begin fighting with each other. Later, back at his apartment, Sidney tells Mike that he is "a nothin'...but would sure like to be a somethin'." Trying to build up the young man's self-confidence, Mike assures Sidney that he can do anything he wants, but is shocked when the novice janitor tells him that he wants to be a policeman.
Though he initially refuses Mike's request that he endorse Sidney's admission to the police academy, Riley relents after hearing Martha's glowing endorsement of Mike's handling of the bumbling Sidney. While helping Sidney fill out his application to the academy, Mike cannot stop talking or thinking about Martha, and when she arrives at Sidney's apartment to check up on the young man, Mike readily agrees to escort her home. The two soon begin seeing each other socially. Sidney's love life also takes a turn for the better when Patricia, an attractive young tenant in his building, reprimands him for not asking her out. Sidney tells the student nurse that he cannot date her until he makes something of himself. Although he struggles every step of the way through his police training, which includes judo and sumo wrestling lessons, Sidney makes it through the initial stages of the academy. Mike becomes so obsessed with helping Sidney, however, that Martha breaks up with him. Meanwhile, Sidney is visited by Monk and Artie, who try to talk him out of becoming a policeman.
Though Monk tells Sidney that the world is against them, Sidney argues that there are a lot of decent people in the world and he is just trying to be one. On his first patrol, Sidney is assigned to walk a beat with Mike in his own neighborhood, and the trainee ends up delivering a baby. Later that evening, however, Sidney gets involved in a police scuffle with his old hoodlum friends, and Artie is shot by his gun. Monk later confesses that the gun fell out of Sidney's holster during the fight, and he accidentally shot Monk while trying to steal the weapon. Cleared of the shooting, Sidney finally receives Riley's full endorsement to join the force, and he rushes home to give Patricia the good news. Later, policeman Sidney L. Pythias meets with his old hoodlum friends and offers them the same encouragement to improve themselves that Mike offered him.