"Young Girls" is a song by American singer-songwriter Bruno Mars. It was composed by Mars, Philip Lawrence and Ari Levine, a songwriting and record production trio known as the Smeezingtons, as well as Jeff Bhasker, and Emile Haynie, with additional songwriter credits by Mac Davis, for Mars's second studio album Unorthodox Jukebox (2012). It is a midtempo, doo-wop-influenced pop ballad that garnered comparisons to Mars's "It Will Rain" and Lana Del Rey's music. Its instrumentation includes drums, synths, piano and elements of electro music. The song was released as the first promotional single and later as the fifth overall single from Unorthodox Jukebox, being first serviced to contemporary hit radio in Australia on November 26, 2013.

"Young Girls" received generally mixed to positive reviews. Many music critics noted the complex instrumental and praised Mars's vocals on the record. Its lyrics, detailing the fact of the singer being unable to resist his attraction to young girls, were met with criticism. The single was recognized as the Best Pop of 2013 at the MelOn Music Awards. Commercially, "Young Girls" charted in some countries, along with the released of its parent album, such as South Korea, where it reached number one, United Kingdom and Canada. Before it was canceled as the second single it peaked in Australia and New Zealand at 62 and 23, respectively. As the fifth single it reached the position of 19 in Canada and 32 in the United States. It was certified platinum by the Recording Industry Association of America (RIAA) and double platinum by Music Canada (MC). The track was performed live on Saturday Night Live and occasionally on The Moonshine Jungle Tour (2013–14).

During a MTV interview, Bruno Mars explained why the track was the first on the track list of the album "It really shows you what this album is going to be, and just where I was when I started" it. He felt that anyone can easily relate to the record "There's a moment in your life where you start going out every night, and it's so fun, but then you start to lose yourself". The singer compared the song's sentiment to "Lookin' for Love in All the Wrong Places", adding "It's another confession". In a different interview Mars furthered the concept of the track as it's about you "losing yourself", which happened to him in L.A. during his early years. He added, "If you're out there wilding out, drinking and partying, that's not real life."

Mars stated that he felt like "an old blues man" when writing the song, and wanted to re-create the sentiment when some young girls were giving him the "runaround". Furthermore, he wasn't willing to stay too far from his roots when it comes to writing lyrics for his album, explaining "I'm not there yet...to sing about politics". He concluded that writing and singing songs about girls is what he knows best, "I'm not going to preach what I don't know. As much as I love 2 Chainz's "All I Want for My Birthday" (2012).

A demo of the song, only featuring the vocals and an acoustic guitar, was exclusively released as bonus track on the Target edition of the album, on December 11, 2012. Almost a year later, on November 5, 2013, the demo of the song was also included on the deluxe edition of the album, released in various countries. The song was re-registered with a new writing credit for Mac Davis. Davis explained he met Jeff Bhasker, who was in the studio with Mars, through Neil Jacobson. Bhasker asked him to come to the studio and at that time they were looking at a rhyme for the chorus. Davis ended up writing the hook. He won a BMI Pop Award in 2015 due to his work on this song.

"Young Girls" was written by Mars, Philip Lawrence, Levine, Bhasker, Emile Haynie and Davis, while production was handled by the former three under their alias, the Smeezingtons, along with Bhasker and Haynie. The song was recorded by Levine at Levcon Studios in Los Angeles and mixed by Manny Marroquin at Larrabee Sound Studios in North Hollywood, California. Charles Moniz served as the track's additional engineer, Brent Kolatalo and Ken Lewis engineered the big drums. It was mastered by David Kutch at The Mastering Place.

"Young Girls" was first performed on Saturday Night Live and was released as the first promotional single taken from Unorthodox Jukebox, on November 6, 2012, on iTunes. Later, it was reported by Mars that the record was scheduled to be the second single from the album. This release involved little planning according to Mars "I felt [it] was good. None of these things are planned, which one goes first, which one goes second. One day I wake up and I say, 'You know what? I want the world to hear this song that I wrote called 'Young Girls,' and I put it out". However, a week later, while performing "When I Was Your Man" on the third-season finale of The Voice, he announced that the track played would be the second official single from the album. The fifth and overall single, "Young Girls", was first released in Australia, on November 26, 2013, after being promoted by Mars in radio station, Nova. Subsequently, the song was issued to United States and United Kingdom contemporary hit radios on December 10, 2013, and February 17, 2014, respectively. Italian radio stations began adding the track onto their playlists on February 26, 2014.

"Young Girls" is a "woeful" midtempo pop ballad. The "pop anthem" is also influenced by a groove from Mars's debut studio album, noticeable on the backing vocals, and it contains elements of "the shaded earnestness" found in "It Will Rain". According to the sheet music, the song is composed in the key of A major with a time signature in common time, and a moderate groove of 125 beats per minute.