Tony Rivers (Michael Landon), a troubled teenager at Rockdale High, is known for losing his temper and overreacting. A campus fight between Tony and classmate Jimmy (Tony Marshall) gets the attention of the local police, Det. Donovan (Barney Phillips) in particular. Donovan breaks up the fight and advises Tony to talk with a "psychologist" that works at the local aircraft plant, Dr. Alfred Brandon (Whit Bissell), a practitioner of hypnotherapy.
Tony declines, but his girlfriend Arlene (Yvonne Lime), as well as his widowed father (Malcolm Atterbury), show concern about his violent behavior. Later, at a Halloween party at the "haunted house", an old house at which several of the teenagers hang out, Tony attacks his friend Vic (Kenny Miller) after being surprised from behind. After seeing the shocked expressions on his friends's faces, he realizes he needs help and goes to see Dr. Brandon.
On Tony's first visit, however, Brandon makes it clear that he has his own agenda while the teenager lies on the psychiatrist's couch: Tony will be an excellent subject for his experiments with a scopolamine serum he's developed that regresses personalities to their primitive instincts. Brandon believes that the only future mankind has is to "hurl him back to his primitive state." Although Brandon's assistant, Dr. Hugo Wagner (Joseph Mell), protests that the experiment might kill Tony, Brandon continues and within two sessions suggests to Tony that he was once a wild animal.
That night, after a small party at the haunted house, Tony drives Arlene home; and one of their buddies, Frank (Michael Rougas), is attacked and killed as he is walking home through the woods. While Donovan and Police Chief Baker (Robert Griffin) review photographs of the victim and await an autopsy, Pepi (Vladimir Sokoloff), the police station's janitor, persuades officer Chris Stanley (Guy Williams) to let him see the photos. Pepi, a native of the Carpathian Mountains, where werewolves, "human beings possessed by wolves", are common, immediately recognizes the marks on Frank's body, much to the disbelief of Chris, who balks at the idea of a werewolf.
The next day, after another session with Brandon, during which Tony tells the doctor that he feels that there is something very wrong with him, Tony reports to Miss Ferguson (Louise Lewis), the principal of Rockdale High. Miss Ferguson tells Tony that she is pleased with him; Brandon has given him a positive report regarding his behavior; and that she intends to recommend Tony for entry into State College. As Tony leaves the principal's office happy with the good news, he passes the gymnasium where Theresa (Dawn Richard) is practicing by herself. A school bell behind his head suddenly rings, triggering his transformation into a werewolf, and he attacks and kills Theresa. Tony flees the high school and, despite the changes in his facial appearance, witnesses identify him by his clothing, causing Baker to issue an all-points bulletin for his arrest.
A local reporter, Doyle (Eddie Marr), interviews Tony's father, as well as Arlene and her parents, in the hope of locating Tony and getting a scoop. Baker and Donovan attempt to trap Tony in the woods where they think he may be hiding. Still in the form of a werewolf, Tony watches as the dragnet looks for him, but is surprised by a dog and ends up killing it.
In the morning, Tony awakens and sees he has reverted to his normal appearance and walks into the town. After phoning Arlene (who answers, but refuses to tell the police who is on the line), Tony heads to Brandon's office and begs for his help. Brandon wants to witness Tony's transformation, and capture it on film in order to advance himself in the scientific community. Brandon tells Tony he will help him and after telling him to lie on the couch, injects him with the serum again. Immediately following the transformation, a nearby ringing telephone triggers Tony's instincts and he leaps up---and kills both Brandon and Wagner---breaking open the film camera in the process, ruining the film. Alerted that Tony has been seen nearby, Donovan and Chris break in and are forced to shoot several times as Tony advances toward them. Upon dying, Tony's normal features return, leaving Donovan to speculate on Brandon's involvement – and on the mistake of man interfering in the realms of God.Michael Landon as Tony Rivers
Yvonne Lime as Arlene Logan
Whit Bissell as Dr. Alfred Brandon
Malcolm Atterbury as Charles Rivers
Barney Phillips as Detective Sgt. Donovan
Robert Griffin as Police Chief Baker
Joseph Mell as Dr. Hugo Wagner
Louise Lewis as Principal Ferguson
Guy Williams as Officer Chris Stanley
Tony Marshall as Jimmy
Vladimir Sokoloff as Pepe, the Janitor
Kenny Miller as Vic
Cindy Robbins as Pearl
Michael Rougas as Frank
Dawn Richard as Theresa
Variety reported: "Another in the cycle of regression themes is a combo teenager and science-fiction yarn which should do okay in the exploitation market [...] Only thing new about this Herman Cohen production is a psychiatrist's use of a problem teenager [...] but it's handled well enough to meet the requirements of this type film. [...] good performances help overcome deficiencies. Final reels, where the lad turns into a hairy-headed monster with drooling fangs, are inclined to be played too heavily." Variety went on to say that Landon delivers "a first-class characterization as the high school boy constantly in trouble."
According to Tim Dirks, the film was one of a wave of "cheap teen movies" released for the drive-in market. They consisted of "exploitative, cheap fare created especially for them [teens] in a newly-established teen/drive-in genre."
The film was very profitable, as it was made on a very low budget but grossed as much as US $2,000,000, compared to its $82,000 budget. Released in July 1957, it was followed four months later by I Was a Teenage Frankenstein as well as Blood of Dracula, and by the sequel How to Make a Monster in July 1958.
Less than four months after the release of I Was a Teenage Werewolf, and coinciding with the release of I Was a Teenage Frankenstein, AIP released Blood of Dracula, a film which bears more than a passing resemblance to their summer box office hit. More or less a remake, and with the hero and villain roles now both played by females." Blood of Dracula, with a story and screenplay credit by I Was a Teenage Werewolf writer Ralph Thornton (a pseudonym for AIP producer Herman Cohen and Aben Kandel), features many other similarities to I Was a Teenage Werewolf: for instance, both have (among other things) a teenager with social behavior problems; an adult mad scientist who is searching for the perfect guinea pig, under the guise of helping troubled youth; an observer who can tell the killings are the work of a monster, a disbelieving police chief afraid of the press, a song written by Jerry Blaine and Paul Dunlap, accompanied by a choreographed "ad-lib" dance number, hypnosis as scientific medical treatment; drug injections, specific references to Carpathia, hairy transformation scenes, and even some of the same dialogue. In addition, two prominent actors from I Was a Teenage Werewolf are also featured in Blood of Dracula, Malcolm Atterbury and Louise Lewis, with Lewis' villain, 'Miss Branding' a practically perfect female version of Whit Bissel's 'Dr. Brandon.' However, few critics have drawn a connection between the two films, and while most reference works consider I Was a Teenage Frankenstein and How to Make a Monster as direct follow-ups to I Was a Teenage Werewolf, not even cinema guru Leonard Maltin speaks of Blood of Dracula as even being related to the trilogy.
I Was a Teenage Werewolf helped launch Landon's career, as he became a regular on Bonanza only two years later, staying for the entire TV show's run. Another actor from the film, Guy Williams, got into big roles for TV later into the 1960s: he first had the lead in the Disney TV Show Zorro, followed by playing Professor John Robinson on the TV show Lost in Space, which also featured other big name stars in regular and guest starring roles. During the Bonanza years, Williams and Landon did appearances together in some installments. Still another star from the film, Whit Bissell, got into sci-fi both on film and TV: he played numerous doctors (good and bad) and then played Gen. Kirk on the short-run TV series The Time Tunnel.
Although today the film is largely regarded as a source of "camp" humor, and while at the time of release the idea of an adult human turning into a beast was nothing new, the idea of a teenager doing just that in a movie was considered avant-garde—and even shocking—in 1957. I Was a Teenage Werewolf likely paved the way for Walt Disney to do his version of a Felix Salten shapeshifting novel, The Hound of Florence. Featuring Disney favorite Tommy Kirk as the hapless teenager, and A-lister Fred MacMurray as the answer to B-lister Whit Bissell, it was released in 1959 under the title The Shaggy Dog. The film betrays its successful forebear with Murray's classic bit of dialogue: "Don't be ridiculous — my son isn't any werewolf! He's just a big, baggy, stupid-looking, shaggy dog!"
The film's Police Gazette-style title (which had already been used by Hollywood previously with pictures such as 1949's I Was a Male War Bride and 1951's I Was a Communist for the FBI) with the inclusion of the adjective "teenage" was used again by AIP for their sequel I Was a Teenage Frankenstein, and the original working title for their 1958 sci-fi film Attack of the Puppet People was I Was a Teenage Doll. Due to the success of I Was a Teenage Werewolf, this convention was constantly mocked in the late 1950s and early 1960s. Many sitcom television series in particular had characters going to movies titled I Was a Teenage Dinosaur, Monster, etc., and it was often referenced in monologues by comedians and bits by disc jockeys. Examples include Stan Freberg's 1957 radio series, which featured a Madison-Avenue/horror-movie spoof titled "Gray Flannel Hat Full of Teenage Werewolves", and the 1959 "Dobie Gillis" novel I Was a Teenage Dwarf by Max Shulman.
Over the years, the "I Was a Teenage..." title was played on by several unrelated films, usually comedies, wishing to make a connection with the cult AIP hit, including Teenage Caveman, the 1963 Warner Bros. cartoon, I Was a Teenage Thumb, 1987's I Was a Teenage Zombie, 1992's I Was a Teenage Mummy, 1993's I Was a Teenage Serial Killer, and 1999's I Was a Teenage Intellectual.
The script title for 1985's Just One of the Guys was "I Was a Teenage Boy," a title that used a year later as an alternate for 1986's Willy/Milly. An alternate title for the 1995 hit Clueless was "I Was a Teenage Teenager."
Scenes from I Was a Teenage Werewolf were included in the 1973 "fifties nostalgia" concert film Let the Good Times Roll, featuring Madison Square Garden performances from Chuck Berry and Bill Haley and the Comets.
Episode 2.19 (1963) of The Dick Van Dyke Show was entitled "I Was a Teenage Head-Writer". Episode 1.18 (1967) of The Monkees was entitled "I Was a Teenage Monster".
The July 16, 1982 episode of SCTV ("Battle of the PBS Stars") featured a comedy skit of the movie called "I was a Teenage Communist," mixing horror with the politics of red-baiting during the 1950s.
In 1987, the NBC-TV series Highway to Heaven featured "I Was a Middle-Aged Werewolf" (episode 4.5), written and directed by Michael Landon. Landon, as angel Jonathan Smith, transforms himself into a werewolf, initially to scare off some teenage bullies. During the earlier scenes, Jonathan's buddy watches the original film, remarking: "You know, the guy in this movie reminds me a lot of you," adding, "when he's a regular guy, not when he's got fuzz all over his face."
In April 1997, the movie was mocked directly when it was featured in episode 809 of Mystery Science Theater 3000. The host segments, meanwhile, parody the film Alien.
The October 28, 1999 episode of SpongeBob SquarePants is titled "I Was a Teenage Gary," and features SpongeBob transforming into a snail after a hypodermic injection.
A Phineas and Ferb episode in 2010 was titled "I Was a Middle Aged Robot". It involves Phineas' dad, Mr. Fletcher, having his imagination sucked away and the O.W.C.A. (Organization Without a Cool Acronym) replacing him with a robot controlled by Phineas & Ferb's pet platypus, Perry, also known as Agent P.
The Cramps, whose songs routinely reference horror and sci-fi films, have a song titled "I Was a Teenage Werewolf" on their 1980 album Songs the Lord Taught Us. Anarchist vegan punk band Propagandhi wrote a song titled "I Was a Pre-Teen McCarthyist" and is featured on the 1996 album Less Talk, More Rock. Rock band Queens of the Stone Age have a song on their 1998 self-titled debut album with the title, "I Was a Teenage Hand Model." Australian rock band Faker released a song in 2005 entitled "Teenage Werewolf." Punk band Against Me! released a song in 2010 titled, "I Was a Teenage Anarchist." Pop punk artist Lil Cam'Ron's debut album I Was a Teenage Cameron also references the title. American Musical Theater Composer Joe Iconis wrote a song titled "I Was A Teenage Delinquent!" on YouTube. Brazilian rock band Legião Urbana has a song called "Eu Era Um Lobisomem Juvenil", title of the movie in Portuguese. Australian band Magic Dirt's 2000 song "Teenage Vampire" is a reference to the film's title.
In Stephen King's 1986 novel It and its made-for-TV film adaptation, several of the characters watch this movie. Afterwards, Pennywise (Tim Curry) takes the form of a real teenage werewolf to frighten them, particularly Richie (Seth Green). When the Losers Club first attacks Pennywise, it takes the form of the werewolf. In 2002, Last Gasp published I Was a Teenage Dominatrix, a memoir by Shawna Kenney. In 2015, the anthology Killer Bees from Outer Space (KnightWatch Press) featured a story, "I Was a Teenage Mummy Girl", by Amelia Mangan.