What a difference a year makes. In the summer of '88, New Kids on the Block was a relatively obscure teen vocal ensemble from Boston touring low on a bill headlined by the season's brightest star, Tiffany. Then came 1989, which may be remembered in the annals of teen idoldom as the Year of the Kids. That Tiffany recently logged time as their opening act is just one measure of the Kids' burgeoning stardom. Their second album, Hangin' Tough, has sold more than 4 million copies, spawned four Top 10 singles and ignited a coast-to-coast teen frenzy. Count 30,000 fan letters a week and 400,000 calls a month to the Kids' 900 phone line, then factor in an upcoming Screaming Room Only concert tour, and it becomes clear that the Kids have ascended to that lofty plane of teen-idol worship once occupied by the likes of Bobby Sherman, the Cassidy brothers, David and Sean, and the Monkees.

Doubters need only tune in to some of the teenspeak overheard at a recent San Diego concert, where the Kids were tuning up for their Nov. 9 tour kickoff in Buffalo, N.Y., and where the hormones were audibly surging. "I like them because I love their music and because they're gorgeous!" burbled Stacey Mooney, 16, a typical member of the young and overwhelmingly female audience. "Gorgeous is the No. 1 reason!"

Passionate in her belief that good works might someday be rewarded, Rachel Christian, 15, announced, "I pray every night and I read the Bible"—all in hopes of meeting a Kid. Tina Tretinjack, 13, said she would cheerfully get herself arrested if it would lead to a close encounter, and daredevil Jenny Short, 14, confided that she would "jump from the top of the theater to the stage" for the same privilege.

Fourteen-year-old Mimi Adamu was tossed out of a Kids concert last summer because, she admits, "I hugged Donnie [Wahlberg] too hard" during an onstage hugging contest. But she's not bitter; she'd squeeze him again in a minute. "Sometimes I feel alone and stuff and I have a certain guy, Donnie, to like," she explains. Why him? "He's live!" That's a term of endearment, not an expression of minimal standards. But it takes Denise Giggleberger, 15, to give voice to the carnal underpinning of many a crush. "I loved it," she says, "when Donnie shook his little butt!"

The squeals of Miss Giggleberger and her friends are music to the ears of the Kids' Svengali, Boston record producer Maurice Starr, who in 1981 put together the group New Edition, a quintet of black teenagers whose intricate dance routines and sweet adolescent harmonies seduced millions of young record buyers. Four years ago, Starr, recognizing a marketing opportunity, began looking for five white kids capable of doing much the same thing. He found them in Wahlberg, 19, and his boyhood pals from the working-class Dorchester section of Boston, Danny Wood, 19, Jon Knight, 19, and his brother Jordan, 18. Fellow Bostonian Joe McIntyre, 16, joined shortly thereafter.

Eager to hitch their wagons to Starr, the Kids admit they weren't prepared to be objects of such mad adulation. "Every day it gets crazier and crazier," says Wood. How crazy? Fans have popped up out of hotel garbage cans, stolen lawn trimmings from in front of the Kids' homes, lain down in front of their limos and, disguised as maids, surprised them in bed. "It gets real scary," says Jon, who was trapped in a hotel elevator by a mob of girls. "It's like they want a piece of you. Grown-up stars have grown-up fans, but we have kids. We're probably like the first group that they've had a crush on."

To cope, the Kids "have fun with it," says Donnie, who, like his mates, enjoys playing role-reversal games with his bodyguards. "Is the room secure?" Joe shouts as he and Danny search their hotel suite. "Yo, Danny! There might be snipers!"

"Don't worry," says Danny. "I'll take the bullet." A tad macabre, but Kids will be kids. "If we don't act crazy," reasons Danny, "we'll go crazy."

—Steve Dougherty, Michael Alexander and Craig Tomashoff in San Diego