"Slumber Party" is a song recorded by American singer Britney Spears for her ninth studio album, Glory (2016). It was written by Mattias Larsson, Robin Fredriksson, Julia Michaels and Justin Tranter, and produced by Mattman & Robin. The duo was also responsible for vocal production alongside Mischke Butler. The song was released as the second single from the album on November 17, 2016. A remix version featuring vocals from American singer Tinashe was sent to US contemporary hit radio on November 22. A reggae-pop and R&B track, "Slumber Party" features brass, marimba, syncopated synths, percussion and a horn section in its instrumentation. Lyrically, the song was described as an ode to fornicating and making sex tapes. In it, Spears evokes one-night stands, the ritual of sleepovers with friends and the teenage game seven minutes in heaven.

"Slumber Party" received positive reviews from music critics, who emphasized its sensual nature. Commercially, the song appeared on the national charts of countries such as Canada, Spain, Scotland and the United States, where it debuted and peaked at 86 on the US Billboard Hot 100, while topping the Dance Club Songs chart. A music video directed by Colin Tilley was shot in October 2016, and according to Spears, has an Eyes Wide Shut (1999) theme. The video was released on November 18, and features Spears and Tinashe during a sleepover-themed masquerade party in a mansion, where they are seen in rooms filled with bubbles, smoke and flashing lights. The video also features Spears's ex-husband Sam Asghari. "Slumber Party" was added to the set list of her residency show, Britney: Piece of Me (2013—2017), and was performed on two of her concert tours.

She interprets the story – whether she's talking about fun and sex or talking about heartbreak, you feel it. [She gives] voice for days. The voice is so specific but it never ends – there's endless possibilities.

In September 2014, Spears posted a picture of herself in the studio, hinting that she was recording new music. A month later, during an interview, she revealed that she was working "very slowly, but progressively" on an album. In 2015, she continued to work on the record, and that November, Spears teased on her Instagram account that she was working with songwriters Justin Tranter and Julia Michaels, by posting a picture of them looking "bemused" with the caption: "Working hard and hardly working...new album...wheeeee!" A month later, Tranter gave an interview for website NewNowNext about his work with Spears, saying: "Working with Britney is a fucking dream. She is so sweet, so inspiring and a master on the mic. Me and Julia had to leave the studio one day because our screams of excitement after every take she did were distracting the producers." In May 2016, in an interview for website Breathe Heavy, he revealed: "Nobody ever talks about Britney as a writer and she's f**king great, like insane. Her concepts were bold and smart and very left of centre, in a good way. Melodically, she has melodies for days. How come no one mentions that this girl can write the f**k out of a song?. [...] "We got to work with her a bunch of times. A couple [of songs] we wrote on our own and then she wanted to write with us. She's an amazing writer."

"Slumber Party" was included as the eighth track on Glory, which released on August 26, 2016. After releasing "Make Me" as the lead single, Spears's team commissioned several polls to different magazines asking which song from the album should be the second single. On October 14, American singer Tinashe hinted on her Instagram account that she was recording vocals on a "legendary" collaboration with the caption: "Dreams are real." Later, on October 25, Spears posted a picture of herself with Tinashe on the set of the song's music video, with the caption: "Neighbors say we're causing a commotion...", a line from "Slumber Party". Billboard confirmed the news with Spears's representatives. Lewis Corner of Digital Spy also announced that the collaboration was going to be released "within a matter of weeks." Spears later commented on Tinashe, stating: "[She] is so sweet. I always see my fans talking about her online, and it just made so much sense to collaborate on this song. She was amazing, and would love to find another way to work together in the future!" The remix version was released on November 16, to digital download. It was sent to US contemporary hit radio on November 22.

During a 2022 interview on Watch What Happens Live with Andy Cohen, English singer Charli XCX revealed that she was asked to be featured on the remix of "Slumber Party", but she had to turn it down due to scheduling conflicts.

"Slumber Party" was written by Mattias Larsson, Robin Fredriksson, Julia Michaels and Justin Tranter, with production done by Mattman & Robin. Mattman & Robin were also responsible for vocal production, alongside Mischke Butler, as well as programming, drums, percussion, snaps, handclaps, synths, guitars, bass, marimba and brass. Michaels, on the other hand, provided background vocals. The song was recorded at 158 Studios in Westlake Village, California, and Wolf Cousins Studios in Stockholm, Sweden, as well as Conway Recording Studios in Los Angeles, California.

"Slumber Party" is really cool because it [...] has a Jamaican feel to it, it's really laid back. I think a lot of girls are gonna have a lot of sleepovers to this song, it's definitely a song you [listen to when] you and your girlfriends go out and just have a great time – eat a lot of pizza and talk about boys and be really naughty.