Under the guidance of Michael Bivins of Bell Biv Devoe, the four-man vocal group Boyz II Men became a pop sensation in 1992. Although they call their music "hip-hop doo wop," there's very little traditional doo wop in it. Instead, they bring the sound of '60s and early-'70s R&B vocal groups into the '90s, adding a little New Jack swing to that timeless sound. Their 1991 debut, Cooleyhighharmony, featured a massive hit single, "Motownphilly" which exemplifies the best of their dance work. Their second single, a ballad called "It's So Hard to Say Goodbye," was an even bigger hit; its success paved the way for "The End of the Road" (taken from the Boomerang soundtrack), the group's follow-up single, which broke Elvis Presley's record for the most weeks spent at number one. After releasing the seasonal Christmas Interpretations album in 1993, Boyz II Men went to work on their second album, which appeared in the fall of 1994. II proved to be even more successful than its predecessor, selling over seven million copies by summer of 1995 and spawning the record-breaking hit "I'll Make Love to You." Evolution followed in 1997.