The song was written by band members Bob Bryar, Frank Iero, Ray Toro, Gerard Way, and Mikey Way, and was produced by the group alongside Rob Cavallo.

The accompanying music video for "Teenagers", directed by frequent collaborator Marc Webb, depicted the band performing in a high school gymnasium before being attacked by a horde of fans.

[1] There, frontman Gerard Way expressed an interest to create an album which explored life and death, but contained his real fears "buried under layers of pomp and circumstance".

[2] "Teenagers" was conceived as part of these early sessions;[1] Gerard Way explained in an interview with Take 40 Australia that the song was primarily written while he was riding the New York City Subway, as he found himself scared of high schoolers in a train car and began to wonder if he was out of touch with the youth.

[16] Instrumentally, the song begins with a simple guitar riff consisting of hammer-on notes and palm muting; a vibraslap can also be heard prior to each chorus.

[21][22] Weingarten additionally noted how "Teenagers" seemed influence by the Slade song "Mama Weer All Crazee Now", while NME also compared the track to those by Roxy Music.

[1] It is distinctive from the rest of The Black Parade in that it does not directly follow the album's overarching narrative about the death of The Patient; Way instead described the song as a "commentary on kids being viewed as meat; by the government and by society".

[27] In an interview with NME, Way acknowledged that gun crime was "a really big problem in America", and noted how the track "almost didn't fit on the record[,] but it's a topic that's so important to our culture".

[19] Wren Graves of Consequence praised "Teenagers" for its "mocking humor" in a retrospective review of the album,[29] while Clark Collis of Entertainment Weekly lauded its "theatrical" nature and Way's "jauntily devilish vocal persona".

However, Sean Howe of The Village Voice criticized the line "If you're troubled and hurt / What you got under your shirt / Will make them pay for the things that they did" for being "too Trenchcoat Mafia for comfort".

[30] The track has performed generally well in rankings of songs on The Black Parade, with both Robert Christgau and Theon Weber of Stylus identifying "Teenagers" as a standout on the album.

[34] "Teenagers" has also been deemed one of the best tracks in My Chemical Romance's discography as a whole, with Rou Reynolds of the band Enter Shikari calling it his favorite due to its catchiness and lyrical content.

[66][67] The video depicts the band performing the song inside a high school gymnasium to a group of teenage fans, while cheerleaders with gas masks and batons dance.

[68][69][70] The music video pays homage to the Pink Floyd film The Wall, with both containing a similar scene of teenagers breaking through a padlocked door.

[82] Additionally, "Teenagers" has been covered by various artists, including by Palaye Royale in live performances,[20][83] Macy Gray,[84][85] Save Face,[86] and Against the Current for the compilation album Rock Sound Presents: The Black Parade.