“Now,” which released volume 6 last week, has sold more than 12 million copies in the United States since the series’ inception in 1998. Hits by current pop superstars have traditionally been the backbone of the series, while the massive TV ad campaign featuring snippets of the artists’ videos (sorry, K-TEL couple) have made “Now” a name brand. “Now 4” became the first compilation ever to hit No. 1 on the charts, “5” has sold more than 3.6 million copies to date (that’s 1-1/2 times more than the first “Now” release) and “6” looks just as promising.

Another reason for “Now’s” success is that it draws fresh material from several major-label conglomerates–Sony, EMI, Zomba and Universal Music–instead of scraping together old hits from one or two flailing labels (a strategy that many previous compilation houses used). The content of each volume is decided by the repertoire committee: an official group of “Now” ambassadors from each participating company. “When you go into a ‘Now’ meeting, you keep your label hat on, but you might tilt it to one side,” says Steve Barnett, executive VP of Epic Records, a label that jumped on the bandwagon at volume 3. “Selling the amount of records that it does, it only makes sense to get your tracks on there.” Virgin Records’ executive VP Ken Pedersen says that peddling singles does not cut into sales of the artist’s full albums, but serves as a “cross-promotional tool” and “time capsule.”

“Now” has built an empire atop the success of boy bands and various Britneys. The concept did, after all, start in Europe, where fleeting hit singles drive the music business (the series is up to “Now 51”). But when the current teen adoration for one-hit wonders blows over, “Now” may be left in the “Then.” That’s why “6” includes artists from outside the bubble-gum arena, like rock veterans U2 and metal’s Incubus and Fuel. " ‘Now’ will evolve as pop radio evolves," says Pedersen. “You’ll always be able to know what’s current in music when you buy ‘Now’.” What better way to avoid the daunting task of turning on the radio and discovering something new?