Commandant Eric (George Gaynes) Lassard decides that the police force is overworked and understaffed, so he comes up with the idea of recruiting civilian volunteers to work side by side with his officers in a program called "Citizens On Patrol" (COP). Lassard hopes to use this program to improve relations with the community. Carey Mahoney (Steve Guttenberg) and his friends Moses Hightower (Bubba Smith), Larvell Jones (Michael Winslow), Eugene Tackleberry (David Graf), Zed (Bobcat Goldthwait), Sweetchuck (Tim Kazurinsky), Laverne Hooks (Marion Ramsey), Bud Kirkland (Andrew Paris) and Debbie Callahan (Leslie Easterbrook) are in charge of training the civilians. The civilians include the enormous Tommy "House" Conklin (Tab Thacker) (who Hightower used to babysit), gung-ho senior citizen Lois Feldman (Billie Bird), Tackleberry's own father-in-law Mr. Kirkland (Arthur Batanides), and skateboarding delinquents Kyle (David Spade) and Arnie (Brian Backer). The latter pair were caught by Capt. Harris (After Sgt. Chad Copeland (Scott Thomson) noticed them starting a riot at the mall), and the judge was about to throw the book at them until Mahoney speaks to the judge to let Arnie and Kyle join the COP program as alternative punishment. The judge agrees to this, and the boys are joined by their unsuccessful attorney, Butterworth (Derek McGrath).Captain Thaddeus Harris (G.W. Bailey) believes "the concept of citizens doing police work is asinine" (even complains to Commissioner Henry Hurst (George R. Robertson)) and is determined to see the COP program fail and take over Lassard's job at the academy. When Lassard leaves on an overseas conference, Harris, along with his right-hand man Lt. Proctor (Lance Kinsey), are put in charge of the academy and Harris immediately plots to make the COP volunteers quit and leave the police work to the officers. The volunteers, however, do well in their training. Mrs. Feldman excels in firing Tackleberry's .44 Magnum, and the two find a friendly bond in each other (given that she reminds Tackleberry of his mother). In training for water safety and drowning victim rescue, Zed "rescues" a cadet but experiences a personal loss of his no longer functioning Mickey Mouse watch, saying it was the last thing he ever stole before joining the academy. Through his loss, Zed gains a love interest, Laura (Corinne Bohrer), a reporter/photographer who has come to the academy to view Lassard's COP program and becomes attracted to Zed. Unfortunately Harris ruins the moment and insults Zed and Laura, which causes Zed to replace Harris' Right Guard deodorant with mace, which burns his armpits.Claire Mattson (Sharon Stone) is a journalist covering the COP program and Mahoney takes it upon himself to impress her. Despite the pranks played upon him (they switch oxygen to helium when Harris demonstrates emergency medical procedures. Gets sent to the Blue Oyster, when he is looking for a good salad bar in town. They even transport Copeland while is was in a porta-potty, by crane, to a crowded stadium and removed the top of the potty just when the National Anthem was about to be played) during the various training exercises the volunteers take, Harris, nevertheless, is still determined to make the Citizens on Patrol program fail.Jones learns that volunteers House, Kyle, and Arnie believe themselves ready to go out and arrest criminals, so Jones, Mahoney, Hightower, and Tackleberry play a prank on the boys, locking the boys in a prisoner transport van with Hightower, who is posing as a Voodoo practitioner who reanimates his "dead" brother, played by Tackleberry, as a Jason Voorhees-esque maniac with a chainsaw to make them take their training more seriously. Later, after being yelled at again by Captain Harris and being called a disgrace, Zed is comforted again by Laura, who says she thinks he is perfect. Mahoney pays Harris back by putting superglue on the mouthpiece of Harris' bullhorn, causing the mouth guard part to get stuck on the rims of his mouth.After several volunteers accidentally foil an undercover police sting (Mrs Feldman interrupts what she thinks is a fencing operation, only to realize that the cops were working the case undercover), the Citizens on Patrol program is suspended, much to Harris' delight. Sometime later, Harris gives some prominent citizens a tour of his precinct when Proctor messes up and is tricked into releasing every inmate at the precinct 19 jail, including a team of ninjas (By being engaged in a game of "Simon says"), and special guest Randall "Tex" Cobb. After the criminals imprison Harris and his guests, they make their escape from the precinct, only to run into Mrs. Feldman, who wastes no time informing the Lassard academy.When Lassard's officers hear of the jailbreak, the COP volunteers are dispatched along with the regular officers to catch the escaped felons. After stopping a robbery and a high-speed air balloon chase (The perps are in a plane and a balloon. Claire and Mahoney get into a plane. Harris and Copeland get into a balloon. Zed, Tackleberry and Sweetchuck get into another plane), the felons are all recaptured. Meanwhile, House, Kyle, Arnie, and Butterworth save Harris and Proctor from drowning in a river after the latter' attempt (and failure) to participate in the chase (Copeland blows a hole in his own balloon and they land in a river), and Zed impresses his girlfriend Laura by saving Sweetchuck's life after they both fall out of a plane in mid-air (after Tackleberry jumps onto the balloon of the felons mid-air). Several of the police chiefs who had gone to witness Lassard's program in action congratulate and compliment Lassard on his program and his officers, much to Harris' dismay.