The film features the film debut of Rita Moreno, billed as Rosita Moreno, and the first major screen role for Anne Francis.
The film begins with three girls fleeing from Elmview Corrective School for Girls, a reform school. Two manage to steal a truck and escape while the third hides nearby. The next day Dr. John Jason (Paul Henreid), a psychiatrist on staff, is told to resign by Riggs (Cecil Clovelly), the chief of staff. Dr. Jason refuses and an investigation in the psychiatrist's methods is begun. Dr. Jason reflects on the circumstances leading up to this day and the scene changes to his arrival at Elmview.
Against the wishes of Riggs, Dr. Jason, is hired to reduce the high rate of recidivism at Elmview. He meets several of the new arrivals and naively recommends treatments for them to Riggs and the other staff, who seem to listen to his advice. Ruth Levering (Catherine McLeod) the assistant superintendent, warns him however that his efforts will be futile. When he follows up and explores the school, Dr. Jason is shocked to discover that not only is his advice not being followed but the girls are forced to work as farm hands and in a sweatshop laundry, and are punished with solitary confinement if they refuse. When he complains, Miss Levering, who had seemed sympathetic to the girls, refuses to back him up. Frustrated and realizing his work will do no good there, Dr. Jason considers resigning, much to the satisfaction of Riggs.
As a passive protest, the girls refuse to sing for the city council when they visit the institution. As punishment, Riggs has Mrs. Beuhler (Grace Coppin), the cruel head matron, confiscate the girls' belongings. In the process Riggs discovers and Beuhler kills a rabbit the girls had been keeping as a pet. In retaliation the girls set fire to their bedding and the blaze destroys the dormitory. Beuhler reacts by bringing the girls to the basement and setting a fire hose on them.
Meanwhile, Dr. Jason and Miss Levering meet on their day off and she explains that if she had supported him with the staff she would be fired and would then be unable to help the girls at all. Though Dr. Jason disagrees with this approach and an argument ensues, a friendship begins between the two. When they return to Elmview, they manage to rescue the girls from Beuhler. One of the girls, Loretta (Anne Francis), a single mother who Dr. Jason tried to help when he first arrived, develops a crush on him as a result.
Threatening to report the fire hose incident to the board of directors, Dr. Jason makes a deal with Riggs where he would stay on in a purely administrative role while Dr. Jason and Miss Levering would make all decisions as to the treatment of the girls. Under the new regime, the harsh punishments are abolished, the farm and the laundry are shut down and replaced by vocational training programs, and a number of other reforms are instituted. The moral and behavior of the girls improves dramatically, though Loretta is jealous of Miss Levering and Dolores (Rita Moreno), a chronic runaway, still has trouble socializing. Eventually Dr. Jason and Miss Levering arrange a dance, inviting boys from a nearby trade school.
The night of the dance, one of the girls "borrows" a bottle of perfume from Mrs. Beuhler who directs her anger at Dolores by cutting off her hair. The rest of the girls go to the dance leaving Dolores in tears. Loretta, hurt by Dr. Jason's rejection of her at the dance, runs back to the dormitory where she finds Dolores has committed suicide. When Riggs sees the body he suspends Dr. Jason and Miss Levering and puts Mrs. Beuhler in charge of the school. Fearing a return of harsh conditions, Loretta escapes with two other girls, Jane and Jackie, as seen at the start of the movie.
Dr. Jason, thinking that Dolores had cut off her own hair, blames himself for not realizing she was suicidal. But Jane emerges from hiding and reveals that Beuhler was actually responsible. At a hearing to determine the fate of Elmview, things don't go well. The suicide and runaways are blamed on Jason's methods and Jane and the other girls refuse to corroborate the incidents with the fire hose or the hair cutting. Miss Levering's testimony is discounted because of her relationship with Dr. Jason.
Loretta and Jackie, now fugitives, visit the maternity home where Loretta's baby is living in an attempt to get money. But on spending some time with him, Loretta decides to keep the baby rather than putting him up for adoption. They learn of Jason's predicament and return to Elmview to testify. With Loretta and Jackie there, the other girls also corroborate their harsh treatment by Beuhler, revealing they had been whipped to prevent them from telling the truth, which leads to Riggs and Beuhler being placed under arrest.
In an epilogue, Dr. Jason and Miss Levering, now Mrs. Jason, are running the school, Loretta is paroled and looking forward to raising her son, and many of the other girls leave to lead productive lives.Paul Henreid as Dr. John H. Jason
Catherine McLeod as Ruth Levering
Cecil Clovelly as Mr. Riggs
Grace Coppin as Mrs. Beuhler
Anne Francis as Loretta
Rita Moreno (as Rosita Moreno) as Dolores Guerrero
Anne Jackson as Jackie
Enid Pulver as Jane
Vorhaus received his idea after he read a newspaper article about abuses at a women's reformatory. Vorhaus and writer Jean Rouverol visited several institutions to gather ideas. Studios initially showed interest, but they backed out since Vorhaus and Rouverol's politics made the studios uninterested; both Vorhaus and Rouverol received blacklists before So Young, So Bad saw release.
The film was shot with a low budget. Filming locations included areas in New York and Connecticut; Manhattan in New York City, Yonkers, and Long Island served as filming locations. A Jewish home for blind and elderly people in upstate New York was used to represent the Elmview Corrections School for Girls, a fictional institution.
Turner Classic Movies described the critical response to So Young, So Bad as "tepid" because independent film-making techniques were not as appreciated in the 1950s as they were in later eras. Many critics made jokes out of the title. Some critics accused So Young, So Bad of taking ideas from Caged. The two films were released one day apart. So Young, So Bad profited in the United States and received an international distribution agreement. Henreid, ignoring the warnings of his agent, placed a 50 percent stake in the film. Henreid said that So Young, So Bad made more money for him than any other film.