The plan was to see The Pink Panther Strikes Again, the fifth film in the Peter Sellers detective comedy franchise. It was March 1976 in Queensland, Australia, and as Chris Patrick’s family prepared for their evening out, someone in the household had left the television on. The sounds of ABBA’s “Mamma Mia” filled the room. Patrick, 13, knew he wasn’t going anywhere that night.

Reluctant travelers from the get go, the Swedish quartet had finally agreed to fly across the globe for a television special in a nation that implausibly had become fixated on the northern European pop band.

It was the first time Patrick had heard them play, and he was transfixed. “I went to get my little cassette recorder, a little tiny thing, and stuck it in front on a stool to record.”

He still has that cassette, as well as an impressive discography of ABBA’s music. Now a professional cellist and arranger in his own right, in 2008, he published ABBA Let The Music Speak , an exhaustive literary effort that chronicles the entirety of ABBA’s musical landscape, because, as he said, someone had to do it.

ABBA, the acronym derived from the first names of band members Agnetha Fältskog, Björn Ulvaeus, Benny Andersson, and Anni-Frid “Frida” Lyngstad, started off as a 1970 Swedish cabaret act named Festfolk. They struggled to break through until they re-formed with a new sound and a new formula that highlighted the vocals of Fältskog and Lyngstad. Soon, they were getting airplay for their early hit "Ring Ring," which they sang in 1973 for the Swedish qualifying competition for the international music competition Eurovision. After a newly minted name change to ABBA, the band returned to try its luck in the competition again the following year, belting out "Waterloo” on stage in a history-making April night to win the 1974 Eurovision, placing them on a path to ’70s megastardom with smashes like “Dancing Queen” and “Super Trouper.”

When Patrick saw the television special, ABBA was playing the hits off of its 1975 self-titled album. At the time, their sound had not yet fully jelled; it would take songwriters and instrumentalists Ulvaeus and Andersson another go before they totally cracked the DNA that made ABBA, well, ABBA.

Now, more than four decades later, ABBA’s music is as relevant as ever. As Mamma Mia! Here We Go Again , a sequel-prequel to the 2008 blockbuster based on the smash 1991 musical, opens in theaters, and as the band plans to release two new songs and reunite as holograms (yes, holograms) for a tour next year, it’s as good a time as any to pose the question: Who and what has kept interest in this odd Swedish experiment in pop going for all these years?

“People have been forced to say, OK, they are still here, obviously they mean a lot to people, and that in itself must mean something,” says ABBA biographer Carl Magnus Palm.

ABBA’s resilience and ability to stay relevant more than three decades after it disbanded is remarkable, especially when you consider the reception to its unique aesthetic. ABBA was unapologetically pop at a time when socially conscious sounds of progressive rock and the revolution demanded by punk dominated the airwaves and the zeitgeist of the time. Preceded by Phil Spector’s “ Wall of Sound ” philosophy, which layered vocals and instrumentals to produce a fuller, deeper sensation , ABBA’s sound was clearly influenced by the Beatles and the growing glam rock scene in the U.K. (That latter inspiration also bled its way into the fantastical outfits the band wore onstage, ostensibly to take advantage of a tax loophole in Sweden that held that stage costumes could get a tax deduction if they were too outlandish to be worn on the street.)

Critics, unsurprisingly, tore ABBA to pieces, dismissing them as artificial, money hungry and cliché. This was especially the case in their home country of Sweden. “The problem with ABBA was not that they lacked skill or talent, but that they were commercial,” explains music scholar Per F. Broman in The Journal of Popular Music Studies . “Sweden is and was a society with strong egalitarian tendencies, in which issues of wealth are particularly problematic.”

Sweden’s tastemakers, namely its influential Music Movement, quickly dismissed ABBA as schlager , a German word they used as an insult against Europop music. It was ABBA’s commercial culture, Broman argues, which made it particularly odious. The progressive music coalition put a bullseye on ABBA, reacting against the band’s non-reactionary lyrics and ABBA’s personal finances. (In order to get around Sweden’s high personal taxes at the time, which Broman estimates were around 80-85 percent, the band invested in everything from oil to property; its manager Stig Anderson’s particularly unabashedly capitalist impulses, likely fanned that fire.)

Internationally, the band was also dismissed by the rock music gatekeepers of the time who couldn’t find the fun or the depth in the quartet that appeared uninterested in responding to the mood of the times. Infamously, in 1979, Village Voice critic Robert Christgau wrote in reference to ABBA, "We have met the enemy and they are them.”

But the fans simply did not care. They made “Waterloo” a smash hit, pushing the ebullient track up on the European and U.S. charts. Then after the international market started to write ABBA off as a one-hit wonder, a resurgence of fandom came from a surprising place: Australia. Aussie fans were taken with this mysterious group from Sweden, becoming enamored with “Mamma Mia” that catchy song that started, unexpectedly, with a marimba.

“Mamma Mia” was never planned to be a single, and RCA, ABBA’s Australian record company had to fight to make it happen. But when they finally succeeded, the song jumped up to No. 1 on the Australian charts for a staggering 10 weeks. That momentum acted like a shot to ABBA’s international reputation. “From Down Under comes this noise, and [Epic Records, ABBA’s UK record company] must have been thinking, ‘What the hell is this? There is still life in ABBA,’” Ulvaeus later reflected .

With the release of its fourth studio album, Arrival, in 1976, ABBA had ascended to superstardom, finding purchase in tracks like “ Dancing Queen ,” and “ Fernando ,” which appeared on the Australian version of the LP. Musically, the band had also fully come into its own by this time with Ulvaeus and Andersson now taking the band’s lyrics as seriously as they took the musical compositions. In turn, ABBA found new ways to relate to its audience, often mining real-life sorrow for art.

ABBA was famously the pairing of two married couples, but perhaps perversely the band kept going after both relationships ended, leading ABBA into untrodden emotional pathos in its later recordings. Just two weeks after Fältskog and Ulvaeus announced on Christmas 1978 they were divorcing, for instance, the band performed a new song “ Chiquitita ” at a UNICEF concert. It’s a heart-wrenching performance, elevated by the real pain going on behind the scenes. “If you look at the opening shot of [Fältskog] singing solo ‘Chiquitita, tell me what's wrong/You're enchained by your own sorrow’ and you look at [Lyngstad], she’s in the back of the frame and she’s looking [on] with this amazing you can do it girl [expression]; you can do it, you’ve got to push through,” Patrick says.

While the band members dressed almost uniformly in black for the concert, perhaps they couldn’t resist adding a few sequins to their costumes, the sparkles in the video footage reinforcing that yes, this was definitely still ABBA taking the stage.

Following the release of The Visitors in 1981, ABBA took a short break. When the foursome came back together the following year to start writing new music, however, it was clear that ABBA’s creative juices were depleted and the group disbanded. In the coming years, ABBA could have been written off as a kooky relic of the 1970s. But instead, it was ABBA’s rejection of the quote-unquote authentic trappings of its more serious peers that kept gay male fans coming back to its music.

Ulvaeus has credited this fan base in particular with keeping ABBA relevant in the years after the band went its separate ways. "In the ’80s ABBA were distinctly 'uncool', totally out of fashion,” as he put it during a 2011 speech . "And I thought 'Well, that's it. It was fun while it lasted, but now it's over. But for some strange reason we still remained popular on the gay scene. And—maybe it sounds like I'm sucking up, but I don't care— when we got a revival in the late ’80s, early ’90s, I'm sure it's because we had stayed popular on the gay scene."

Palm, the ABBA biographer, agrees with that idea. Considering just how astronomically popular the band was at its zenith, he says there was no way ABBA would just go away, and by the late ’80s, Palm says, it had become increasingly clear that gay men were among those keeping the music going, having never stopped loving ABBA. This was post-Stonewall, and at the height of the AIDS epidemic. The appeal of ABBA likely had something to do with escapism. “The “ Gimme! Gimme! Gimme! (A Man After Midnight) ” and “ Voulez-Vous ,”--they’re about clubbing and hedonism and having a good time despite everything,” Palm says.

But unlike, say, the Beatles, there was little to no critical interest in ABBA’s staying power. “I’m not sure there was a critical conversation,” says Palm, who first began studying ABBA himself in the ’80s. “[ABBA was] dismissed as very lightweight; what could there possibly be to say about them? If they were talked about in that sense, it was more like they represented everything that you shouldn’t be. They didn’t have a political message and they didn’t care about that sort of thing. Not overtly at least. I think they were just a symbol for uninteresting music.”

Yet ABBA fans maintained their interest. The official international fan club for ABBA, inaugurated in 1986, was populated by a generation that grew up with the music. Younger fans also joined in. (Today, the community still hosts an ABBA Day in the Netherlands, which goes on for, in fact, several days, an almost ritualistic trek for the truly dedicated.)

“One thing I’ve noticed with ABBA fans is they’ve had such a hard time of it,” says Palm. “If you’re a Beatles fan that’s easy because everyone loves the Beatles, whereas with ABBA there was a long time when you had to hide that fact… so maybe ABBA fans are even more eager to hold onto the fan community because they know this is a safe space. No one will ever laugh at me here. They will just respect me for being an ABBA fan.”

Emerging tribute bands reinforced that ABBA’s longevity was at least, in part, due to the appealingly camp aspects of the band. In the 1980s, songs like “Dancing Queen” became iconic fixtures on the drag scene. And in more mainstream culture, parody bands like Björn Again, which first debuted in 1989, also got their start by toying with ABBA’s kitschy appeal. “They weren’t so careful about the costumes, they just [parodied] these four ABBA members as these ‘dumb Swedes’ who could barely speak English,” says Palm.

These ABBA-inspired groups coincided with the popularity of the 1994 Australian cult classic The Adventures of Priscilla, Queen of the Desert , which culminates in a drag performance of “Mamma Mia.” That same year the heavily ABBA-influenced Muriel’s Wedding also debuted in Australia. While not openly queer, the plot is told through the outsider narrative of a social outcast, doubling down on ABBA’s ability to reach audiences that felt left out of the mainstream.

By this time, it had become clear that ABBA was around to stay. ABBA Gold , released in 1992 was a staple on the top-40 charts, and the Mamma Mia! musical debuted in London to great acclaim seven years later. Ulvaeus had initially rejected the idea of a jukebox musical based on ABBA’s songs when show producer Judy Craymer first approached him about it in the late ’80s, but he later had a change of heart, and after the show was greenlit, it became a smash hit, going on to become one of the longest-running shows in Broadway history in the U.S.

An ABBA resurgence was suddenly in full swing, and with that came a push to confine ABBA within the acceptable mainstream. Against the backdrop of the ’90s culture wars, ABBA’s image was repackaged in a way that emphasized its “wholesome,” “clean” sound performed by two heterosexual married couples, thank you very much. Essentially, ABBA’s legacy was being straightened.

A second wave of ABBA tribute bands presents a good example of this dynamic, says Tracy McMullen, an associate professor of music at Bowdoin College. These acts were obsessive about capturing what they considered to be the integrity of the original band down to the exacting detail. They made themselves into clones, dressing in the very same costumes ABBA once wore and playing with ABBA’s original backup singers.

“These tribute bands will say, well this is the real ABBA. They’re ‘real’ because they’re not drag. The idea is that drag doesn’t get to be seen as recreating or reperforming in a real way,” says McMullen, who examines these tribute bands for her upcoming book, Hauthenticity: Musical Replay and the Fear of the Real . These tribute bands, still going strong today, have put their own claim on what ABBA’s music and legacy means, erasing the queer read of the music and instead situating it in reassuring, square nostalgia .

It was around this time, too, that the critics decided ABBA was actually good. Rather than consider why ABBA had become part of the gay canon, these rock-and-roll gatekeepers of the ’70s were back and now pushing their ideas of “authenticity” onto ABBA’s music to explain its lasting appeal. In the 2013 BBC documentary The Joy of ABBA , the Sex Pistols' founding bassist Glen Matlock admits to being influenced by ABBA, even lifting from the ABBA song “SOS” for the riff in “Pretty Vacant.” ABBA was suddenly being embraced in the canon of popular music.

What Mamma Mia! the musical and movie did to this push and pull over the interpretation of ABBA is hard to say. On the one hand, the storyline—a escapist romp of a script about a young woman’s attempt to find her real father by inviting three of them to her wedding—can be viewed through the lens of camp. Or it can be taken as a tale of that reinforces the embrace of ABBA that McMullen terms as “safe, white, middle class, and heterosexual.”

For their part, the former members of ABBA have welcomed Mamma Mia! . The 2008 movie adaptation starring Meryl Streep and Amanda Seyfried even helped propel the building of ABBA: The Museum in Stockholm, something the band had long resisted. “For them,” says Ingmarie Halling, the museum’s creative director, “it felt like being almost dead to be in a museum, so that’s the reason they didn’t want to do it in the first place.” But fans had been asking for a place to pay tribute to ABBA, and finally, after Mamma Mia! ’s success, she says, “[the band] understood that people were asking for this and the museum was built.”

Chris Patrick, meanwhile, had finally decided to write his book after a reader of his monthly column for an Australian ABBA listserve urged him to compile his thoughts on ABBA’s musical underpinnings.

All those years, he had been considering what made ABBA’s music such an earworm. He remembers bringing up ABBA at his music consortium in the 1980s and being rebuked because “ABBA is not worth putting in the same room” as other bands of “elite thought.”

But time caught up with Patrick’s taste. In the book he breaks down ABBA’s songs that were now being embraced by a new generation. Take the minor key, which made its way into many Andersson-Ulvaeus hits and dampers the joyfulness of their lyrics to create a sort of Dionysian whole. “The minor key is the melancholy key and ABBA does it so well because they come from a place where it’s dark most of the year; they have a few months of summer, and the rest of the time it’s all dark and snowy and gloomy and that’s why they’re masterful writers of melancholy,” he says.

Fältskog and Lyngstad’s vocals, meanwhile, he puts in a league of their own “with Frieda being a very husky mezzo soprano and Agnetha being a high, almost shrieky soprano, as she’s demonstrated in some of these really astronomically high vocals that the boys made them sing,” he says. “The chemistry of combing those two voices together when you listen to them in unison you can’t tell either of them. It’s just a one voice sound.”

When ABBA broke up, Patrick said he had resolved to let go of any hope of a reunion of the band. “I just thought I’m very happy to let go,” he says. Yet at the same time, a part of him sensed a reunion might happen one day if the right catalyst came along.

Now that appears on the horizon with the upcoming ABBAtar tour and two confirmed new tracks on their way with the first song, “I Still Have Faith In You,” set to premiere in a televised special this winter. When the new music unfurls, whatever direction it takes, the reception will be different than it was when ABBA first stepped out onto the international stage.

Says Palm of where ABBA stands in modern times, “Today they are taken more seriously because they went away and then they came back and they never went away again.”