To say Britney Jean Spears set the musical bar high for herself is a vast understatement. The Kentwood, Louisiana, native’s 1998 debut single, the hope-springs-eternal, gum-snapping “Baby One More Time,” topped the charts in well over a dozen countries and has been covered by artists such as Travis, Fountains Of Wayne, and Ariana Grande. The video, of course, has become one of the most iconic clips of all time — something spoofed on Glee, parodied (in a slightly-more-raunchy way) by Kate Upton on Lip Sync Battle, and referenced in the video for Anne-Marie’s “2002.”

Yet this track is hardly the most interesting song on her 1999 debut album, …Baby One More Time, released 20 years ago this past Saturday. That honor goes to the album’s final track, a cover of Sonny & Cher’s swinging 1967 mod-rock hit “The Beat Goes On.” Spears’ version is basically her doing karaoke to the electro-swirled 1998 revamp of the song recorded by UK troupe The All Seeing I, who has a co-production credit on the song. That’s not a bad thing at all: The All Seeing I version of “Beat Goes On” cribbed the vampy vocals from Buddy Rich’s 1967 cover of the tune, and Spears stretches her own voice in a similar fashion above crashing drums and scratchy, syncopated chords. It’s understated but sophisticated, and feels like it would suit both the dancefloor of a jazz club and a nightclub.

Oddly enough, Spears’ “The Beat Goes On” also very transparently felt like a record label capitalizing on an existing hit and providing listeners with something familiar to cling to; in other words, the kind of gambit used when the powers-that-be are unsure if an album from a new artist can stand on its own. It’s a curiously insecure choice, since …Baby One More Time easily ended up a multiplatinum #1 smash, no doubt because the album dovetailed with multiple then-hot trends.

The teen-pop craze was already in full swing thanks to Hanson, Spice Girls, Backstreet Boys and ‘N SYNC, and Billboard’s 1998 year-end singles chart was also dominated by solo female performers, including (to name a few) Brandy, Monica, LeAnn Rimes, Shania Twain, Mariah Carey, Missy Elliott, and Celine Dion. The collaborators behind …Baby One More Time’s music — especially the Swedish contingent led by Max Martin, who was enjoying hits with Backstreet Boys and Robyn — were also riding high.

Spears herself was already a poised show business veteran who had appeared on Star Search and a reboot of The Mickey Mouse Club, and was excited for big plans to guest star on Dawson’s Creek. (Despite talking up filming plans in multiple interviews, the role — and a TV development deal — sadly never materialized.) In 1999, Jeff Fenster, senior vice president of A&R at Spears’ label, Jive Records, told Rolling Stone, “For any artist, the motivation — the ‘eye of the tiger’ — is extremely important. And Britney had that. This is clearly a self-motivating person from a very young age.”

But this wasn’t just C-suite lip service and, like most 17 year olds, Spears was a bundle of contradictions not easily pigeonholed. Despite her TV background, the musician — whose idols were Whitney Houston and Prince, Billboard revealed in an October 1998 feature — was refreshingly down-to-earth. According to her 1999 Rolling Stone cover feature, she dug the movie Steel Magnolias, read Cosmopolitan, and dubbed South Park “sacrilegious” — but had a fake ID so she could go drinking with her older brother.

Even more important, Spears emphasized that she was an ambitious teenager who knew what she wanted from her image, music and career. In an early Canadian interview, when talking about a stylist for an upcoming tour, she said, “We had someone come in, but I sort of took over, ‘This is what I want. I want to look like this.'” She told another interviewer that she was initially set to record music indebted to Natalie Imbruglia, and revealed to Rolling Stone her original direction was, “Sheryl Crow music, but younger — more adult contemporary.”

Yet when her music became slicker and more pop-leaning in the studio, Spears was happy: “It made more sense to go pop, because I can dance to it — it’s more me.” And even though she alluded in the Canadian interview that her musical direction was guided for her because she ran out of time to pen original music (“When I really started realizing I need to start writing, it was kind of too late. They had most of the songs picked for the album”), she still wasn’t going to let others control her like some Top 40 puppet.

“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 was one of those songs you want to hear again and again,” Spears told Billboard in October 1998. “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 other interviews, she asserted even more agency over her public persona. “I asked them to change the words to ‘Born To Make You Happy.’ It was a sexual song,” she told Rolling Stone. “I said, ‘This may be a little old for me.’ Because of the image thing, I don’t want to go over the top. If I come out being Miss Prima Donna, that wouldn’t be smart. I want to have a place to grow.”

Anyone who’s followed Spears’ career even in a cursory way (or spun her 2007 album Blackout on repeat) realizes how remarkably prescient that quote was, since she quickly became a pop pace-setter. But because there was no exact blueprint for an artist like her, …Baby One More Time took more liberties with material. The album sounds like Spears is trying on different sonic personas to see what she likes, akin to someone trying on different outfits before a date. “Thinkin’ About You” is a sunny soul tune; “Soda Pop” has a reggae vibe courtesy of breezy rhythms and vocal guest Mikey Bassie; and “I Will Be There” is an obvious cousin of Robyn’s kicky pop. Thanks to another one of Spears’ early collaborators, producer Eric Foster White (Whitney Houston, Bryan Adams) …Baby One More Time also nods to R&B-influenced adult contemporary pop, in the form of the the midtempo duet “I Will Still Love You” and syrupy ballad “From The Bottom Of My Broken Heart.”

…Baby One More Time’s rollout was also extremely wholesome. The album was preceded by a promotional deluge that included trips to radio stations, the L’Oreal Hair Zone Mall Tour, and a stint opening for then-superstars ‘N SYNC. (If these strategies sounded familiar, it’s not your imagination: In the late ’80s, teen-pop star Tiffany followed a similar marketing blueprint to achieve her own superstardom.) Accordingly, the album’s overall lyrical focus hews toward G-rated takes on gooey romance and breathless, perfect love; sample lyrics include “You are my summer breeze, my winter sun, my springtime soul, my autumn touch of gold.”

Since Spears emerged on the cusp of the online revolution, she also had a primitive 1999 website full of senior picture-esque photos and a charmingly antiquated song, “E-Mail My Heart” that nevertheless captured the digital dread we all experience waiting for that important text or message: “It’s been hours, seems like days, since you went away/ And all I do is check the screen to see if you’re OK.”

As …Baby One More Time took off, Spears began to become bolder. Although the album contains the original version of “(You Drive Me) Crazy,” Spears re-recorded the song’s vocals in May 1999 for a remix that appeared in the Melissa Joan Hart and Adrian Grenier teen rom-com Drive Me Crazy. Just months after the album hit stores, her delivery and enunciation exude far more confidence and bite, making what became known as “The Stop Remix!” far superior. She also became more willing to speak out about matters that affect her personally. In a video interview from 1999, she called out the double standards faced by women in the industry after the reporter asked her if she’s bothered that she’s built up to be a sex symbol.

“If they look at me and they see that then, you know, that’s flattering,” she responded. “I mean, that’s fine — I’m just being myself. I’m just being me.” As Spears continues this thought, and references the “Baby One More Time” video, she continues to be gracious, but her annoyance is obvious. “But I just think it’s really funny though that, you know, just by me doing the ‘Baby’ video and with my belly showing or whatever — I mean, I love Backstreet Boys and ‘N SYNC, but when they’re doing all those thrusts on the stage, and when they’re [doing the] making out with the microphone thing no one says anything about that. But when I’m just showing the little belly, everyone’s like, ‘Ooh!’ You know what I mean?”

Spears’ irritation also might stem from the fact that the video’s premise was her idea. “They had this really bizarre video idea, this animated Power Ranger-y thing,” she told Rolling Stone. “I said, ‘This is not right. If you want me to reach four-year-olds, then OK, but if you want me to reach my age group…’ So I had this idea where we’re in school and bored out of our minds, and we have Catholic uniforms on. And I said, ‘Why don’t we have knee-highs and tie the shirts up to give it a little attitude?’ — so it wouldn’t be boring and cheesy.”

Her intuition was right, of course, because she understood how other teenagers viewed the world and fashion, and wasn’t interested in promulgating some adult’s version of adolescence. And Spears’ insistence on releasing music and visuals that reflected her still-forming worldview, with all its complications and occasional incongruities, went a long way to legitimize not just her own career, but teen-pop in general. She certainly paved the way for late ’90s peers Christina Aguilera, Mandy Moore, and Jessica Simpson. But her willingness to go out on a limb for her convictions continues to resonate and reverberate through today’s pop landscape and even inform her own career; after all, just a few weeks ago, she even cancelled her upcoming Las Vegas residency to be with her father as he recovers from a serious illness. …Baby One More Time can occasionally feel like a relic from another time — but its influence on modern music is incalculable.