...Baby One More Time is the debut studio album by American singer Britney Spears. It was released on January 12, 1999, by Jive Records. Spears had been a child performer on The All-New Mickey Mouse Club from 1993 to 1994, and was looking to expand her career as a teen singer. After being turned away by several record companies, Spears signed with Jive for a multi-album deal in 1997. She travelled to Sweden to collaborate with producers Max Martin and Rami Yacoub, who had been writing songs with producer Denniz Pop and others, for ...Baby One More Time. Their collaboration created a pop, bubblegum pop, dance-pop, and teen pop record, with Spears later saying that she felt excited when she heard it and knew it was going to be a hit record. The album was completed in June 1998.

Upon its release, ...Baby One More Time garnered mixed reviews from music critics, with many praising its commercial appeal but deeming it silly and premature. Despite its initial mixed reception, it helped Spears receive a nomination for Best New Artist at the 42nd Annual Grammy Awards (2000). Retrospectively, it has been hailed for its major impact on pop culture, and has been deemed one of the most influential pop records of all time. A massive global commercial success, it made Spears the fifth artist under the age of 18 to top the US Billboard 200. It has been certified 14× platinum (diamond) by the Recording Industry Association of America (RIAA). Spears's best-selling album, it has sold over 25 million copies worldwide, making it one of the best-selling albums of all time, as well as the best-selling debut album by a teenage female artist.

...Baby One More Time produced five singles. The lead single, "...Baby One More Time", brought Spears tremendous global success, reaching number one in most countries it charted in and becoming one of the best-selling physical singles of all time. In 2020, it was named the greatest debut single of all time by Rolling Stone. Subsequent singles "Sometimes" and "Born to Make You Happy" peaked within the top ten in most international countries while "(You Drive Me) Crazy" became Spears's second US Billboard Hot 100 top-ten hit. Spears heavily promoted the album through interviews and televised performances. Furthermore, she embarked on her first headlining concert tour, entitled ...Baby One More Time Tour (1999) and later continued with (You Drive Me) Crazy Tour (2000).

"I had been in the studio for about six months listening and recording material, but I hadn't really heard a hit yet. When I started working with Max Martin in Sweden, he played the demo for 'Baby One More Time' for me, and I knew from the start it one was [sic] of those songs you want to hear again and again. It just felt really right. I went into the studio and did my own thing with it, trying to give it a little more attitude than the demo. In 10 days, I never even saw Sweden. We were so busy."

In June 1997, Spears was in talks with then-manager Lou Pearlman to join the female pop group Innosense. Her mother, Lynne Spears, asked family friend and entertainment lawyer Larry Rudolph for his opinion and submitted a tape of Spears singing over a Whitney Houston karaoke song along with some pictures. Rudolph decided to pitch her to record labels, which required a professional demo. He sent Spears an unused song from Toni Braxton; she rehearsed for a week and recorded in a studio with an audio engineer. Spears traveled from her hometown Kentwood, Louisiana, to New York City with the demo and met executives from four labels, returning to Kentwood the same day. Three rejected her, arguing audiences wanted pop bands such as the Backstreet Boys and the Spice Girls, and "there wasn't going to be another Madonna, another Debbie Gibson or another Tiffany." Two weeks later, executives from Jive Records returned calls to Rudolph. Jive's senior vice president of A&R Jeff Fenster stated: "It's very rare to hear someone that age who can deliver emotional content and commercial appeal. [...] For any artist, the motivation—the 'eye of the tiger'—is extremely important. And Britney had that."

Jive soon appointed Spears to work with producer Eric Foster White for a month, who reportedly shaped her voice from "lower and less poppy" delivery to "distinctively, unmistakably Britney." One of the first songs Spears recorded with Foster White was "From the Bottom of My Broken Heart", which was released as the album's 4th single. Foster White also produced "Autumn Goodbye", which was the B-side to Spears' debut single "...Baby One More Time". During the same session for "Autumn Goodbye", Spears and Foster White also worked on a song called "Love Is On", which ultimately did not make the album and was later given to Sharon Cuneta. Spears recorded a lot of material with Eric Foster White, such as "Autumn Goodbye", "E-Mail My Heart", "From the Bottom of My Broken Heart", "I'm So Curious", "I Will Still Love You", "Way It Is Loving You", "I'll Be There For You", "Soda Pop", "Thinkin' About You", "Nothing Less Than Real", "Wishing on a Falling Star" and a cover of "You Got It All" by the Jets. She also recorded a cover of Sonny & Cher's 1967 single "The Beat Goes On". White was responsible for the vocal recording and song production, while additional production was handled by English electronic music group All Seeing I. After hearing the material, Jive Records president Clive Calder ordered a full studio album.

Spears flew to Cheiron Studios in Stockholm, where half of ...Baby One More Time was recorded from May 1998, with producers Max Martin and Rami Yacoub, and contributions from others, including songwriting from Denniz Pop, who was too ill to attend any recording sessions. Martin showed Spears and her management a track titled "Hit Me Baby One More Time", originally written for American group TLC, who had rejected it. Spears later said that she felt excited when she heard it and knew it was going to be a hit. "We at Jive said, 'This is a fuckin' smash'", revealed the label's A&R executive, Steven Lunt; however, other executives were concerned that the line "Hit Me" would condone domestic violence, and later revised it to "...Baby One More Time". Spears revealed that she "didn't do well at all the first day in the studio [recording the song], I was just too nervous. So I went out that night and had some fun. The next day I was completely relaxed and nailed it. You gotta be relaxed singing '... Baby One More Time'." By June 1998, the album had been completed.

Spears originally envisioned "Sheryl Crow music, but younger – more adult contemporary" for ...Baby One More Time, but acquiesced to the wishes of her label, since "It made more sense to go pop, because I can dance to it—it's more me." The album opens with its lead single, "...Baby One More Time", a teen pop and dance-pop song beginning with a three-note motif in the bass range of the piano. Its opening was compared to many other songs, such as "We Will Rock You" (1977), "Start Me Up" (1981), "These Words" (2004) and the theme song of the film Jaws due to the fact the track "makes its presence known in exactly one second". According to Blender, "...Baby One More Time" is composed of "wah-wah guitar lines and EKG-machine bass-slaps". Claudia Mitchell and Jacqueline Reid-Walsh, authors of Girl Culture: Studying Girl Culture: A Readers' Guide (2008), observed that the lyrics of the song "gesture toward [Spears] longing for the return of an ex-boyfriend." "(You Drive Me) Crazy" runs through a moderately slow dance beat, and has an R&B melody mixed with edgy synthesized instrumentals. "Sometimes" is a ballad, which Spears begins with the lines "You tell me you're in love with me / That you can't take your pretty eyes away from me / It's not that I don't wanna stay / But every time you come too close I move away". Stephen Thomas Erlewine of AllMusic noted the song has "a catchy hook and endearing melody, with a reminiscent euro-dance rhythm."