As the classic origin story goes, the five teenage singers in Philadelphia’s Boyz II Men snuck into a Bell Biv Devoe concert to meet the famous R&B group’s Michael Bivins. They sang for him on the spot; other performers on the bill such as Paula Abdul and Will Smith stopped to pay attention; and Bivins later signed Boyz to a management deal. By early 1992, they’d sold 3 million copies of their debut “Cooleyhighharmony.”

Morris, Wanya Morris and Shawn Stockman are the three remaining singers in Boyz II Men, whose massive early-’90s hits “Motownphilly,” “End of the Road” and “It’s So Hard to Say Goodbye to Yesterday” helped turn them into the best-selling R&B group ever. The band’s perfectly interlocking harmonies came along when Whitney Houston, Mariah Carey and, yes, BBD were delivering immaculate singing to the pop charts. They were part of the electronic, heavily produced new-jack-swing movement, but as their hit cover of the Five Satins’ “In the Still of the Nite” showed, they had doo-wop at their core.

Boyz II Men began with Nathan Morris and Marc Nelson, a friend from High School of the Creative and Performing Arts in Philly. They brought on Wanya Morris, Stockman and Michael McCary, who would provide the group’s distinctive, deep-voiced, spoken-word asides. After the fateful convention center concert, Bivins called with a deal, and by 1991 they were posing in shearling coats on the cover of “Cooleyhighharmony” and dominating just about every radio station.

“Shawn and I were actually in a car driving back to my house, and we just turned on the radio and happened to hear (‘Motownphilly’) on the radio. Things pretty much changed overnight,” Nathan Morris says. “We jumped on the road and started a promotional tour that was 10 months long. We drove across the country in a 14-passenger van for two months. Once we came back, and that new year kicked in, it was a whole new thing.”

For the first album, Boyz wrote or co-wrote more than half of the songs, with Bivins as one of the executive producers. After “Cooleyhighharmony” became such a force, Morris says, executives from the group’s label, Motown, began to pay much closer attention, hiring big-name producers such as Babyface and Jimmy Jam and paying for more expensive recording sessions.

“They wanted to control everything and write the songs and have these checks come out of the budget,” Morris says. “It became pretty absurd. I was more on the business side — I lost a lot of the battles that we should have won.

The follow-up, 1994’s “II,” was just as huge. “The fluffy stuff, it looks like we won,” he continues, “but on the back end, in the business sense, we didn’t win, because it was little old me fighting against (then-President and CEO) Jheryl Busby and Motown.”

Boyz’s reign on the charts dwindled throughout the ’90s, until the band went the way of other venerable boy bands, and evolved into a reliable oldies act. Their five-year Las Vegas residency continues through April, and they put out the doo-wop covers album “Under the Streetlight” last year.

“We found some different harmony structures and chords and stuff we’d never quite heard before, because we’d never listened so intentionally to it,” Morris says.

Steve Knopper is a freelance writer.