When it came to creating their latest musical, Mamma Mia!, Bjoern Ulvaeus and Benny Andersson knew what their fans wanted to see, and that was ABBA.

They also knew what they themselves didn't want to see, and that, too, was ABBA.

You could hardly blame them. As one-half of the Swedish pop institution, Ulvaeus and Andersson lived the ABBA story between 1972 and 1982, and, as Ulvaeus points out in a recent interview in Toronto, framing the band's formative years for the stage was "out of the question."

Then they were presented with another idea: Create a play that has both nothing and everything to do with the band that inspired it.

The musical Mamma Mia! begins in previews at Toronto's Royal Alexandra Theatre on Thursday. The official gala opening takes place May 23.

Already a smash in London, where it debuted last year, Mamma Mia! is a coming-of-age story that centres around a divorced mother and her about-to-be-married daughter. The narrative is written around 22 ABBA songs, which the characters perform to highlight the action.

"From the beginning, Benny and I agreed that the story was the important part here," says the neat, mannerly Ulvaeus, 55. "What surprised us was how easily the songs could be adapted to another story. It was uncanny."

Mamma Mia! actually was set in motion nearly a decade ago at the suggestion of producer Judy Craymer, with whom Ulvaeus, Andersson and famed lyricist Tim Rice had created an unsuccessful '80s musical, Chess.

Ulvaeus and Andersson were unsure, but agreed on the condition that they find a good story.

"I was in London with my wife and two daughters, and we went to see Grease," says Ulvaeus, who has three children with second wife, Lena, and two from his previous marriage to ABBA's Agnetha Faeltskog.

"That night, I could see this enormous potential for a family-oriented musical -- uplifting, romantic, and, above all, with lots of hits in it. Coming out of that theatre, I was 100% for it."

The team enlisted British playwright Catherine Johnson, who was presented with one rule: "If songs had to go, even if they were very famous, they had to go," Ulvaeus says. "Therefore, we don't have Fernando, Waterloo, and others."

Still, says the songwriter, "Most of my songs are small narratives. Knowing Me, Knowing You was about a divorce. In the show, it's a father telling his daughter, who's about to be married, what a divorce can do to you."

It's inevitable that most of the tens of thousands of people who will see Mamma Mia! over the course of its Toronto run will bring with them their own ABBA ideas and memories.

But the songs weren't the only thing to outlive the group.

Ulvaeus and Andersson still work together in their Stockholm studio, Mono, continuing a songwriting partnership that pre-dated ABBA, which they formed with Faeltskog, and Andersson's partner, Anni-Frid "Frida" Lynstad.

"It was such a hurry," Ulvaeus says of ABBA's early days. "We had a hit with Ring Ring Ring and put together the first album very quickly."

Then there was the group's famous 1974 Waterloo victory at that bastion of disposable European pop, the Eurovision song contest.

Ulvaeus says, "People thought we had to be a one-hit wonder. We clawed our way back with S.O.S. and Mamma Mia. Having written those, we felt total artistic and economic freedom and never again had people breathing down our necks. We just wrote and this is what happened."

Ironically, it was the much-documented collapse of the ABBA marriages -- Ulvaeus and Faelkstog's in 1978, Andersson and Lynstad's in 1980 -- that inspired some of their best work. Still, given the uncomfortable prospect for future albums, ABBA called it quits in 1982.

Eighteen years after that split -- almost double the length of time they were together in the first place -- the group still prompts much of the same fan feeling it did in the '70s, especially since the release of 1992's 18-million selling best-of CD, ABBA Gold.

Even Mamma Mia! writer Johnson remembers when it became safe to like ABBA.

"In the original days, I was very much into punk music and working in a record shop," she says with a laugh. "It would have been so uncool to admit to liking ABBA. I later realized that they were good pop songs. It was so timeless."

However, there are moments Ulvaeus prefers to forget.

"Oh my God!," he says, chuckling. "But I won't tell you which ones. Especially on the first couple of albums, there are a couple of songs that I am not proud of."

As for the widely publicized demand for an ABBA reunion tour, with promoters reportedly offering $1 billion? No dice.

"You need more motivation (for a reunion) than money," Ulvaeus says. "We'd have to feel some kind of urge to write more songs and record a new album. Benny and I want to write for the theatre, and heaven knows what the girls are doing right now. So that puts a stop to it."

It also doesn't hurt that 25-year-old efforts are still paying off.

"That is fortunate," he says. "But as the offers to tour present themselves, there is a great joy in having credibility. It's worth so much more than anything we could be paid."