WATERLOO - They live at Starbucks and Cup of Joe. They hang out, sipping lattes, mochas and cappuccinos, conversing about everything from the meaning of life to who's taking whom to prom. They can distinguish an Americana blend from a Sumatra with a single sniff.

They are 15-year-old Emily Dunlay and 17-year-old Allison DeWolf.

They are who the coffee renaissance has been waiting for: a generation too young to remember when coffee wasn't cool.

They were born in the late-1980s, just as Starbucks was raising its first green awnings. They have never associated the drink with truck drivers in seedy diners or salesmen with bad breath.

They grew up with enticing images of coffee, in their own neighborhoods and on TV: grunge rockers brooding in hipster coffee bars, the sexy "Friends" at Central Perk, and Rory, the savvy teen protagonist on The WB's "Gilmore Girls," whose coffee addiction is a regular plot line.

It's no wonder that coffee is now, like super-straight hair, sparkly lip gloss, ironic T-shirts and low-slung jeans, just another way to be cool.

Nearly a quarter of ninth-grade girls drink caffeinated coffee, according to one national survey, with vanilla latte the hands-down favorite among teen girls. NPD Group has market research that shows the number of teens drinking coffee in cafes or restaurants has increased 12 percent since last year, on top of a 15 percent rise the year before.

Coffee's image has come a long way. After World War II, "coffee was perceived as an old-fashioned drink of the older generation, of businessmen and gossiping housewives," explains Mark Pendergrast, author of "Uncommon Grounds: The History of Coffee and How It Transformed Our World."

Then came the beatnik cafes of the 1960s, which introduced fringe types to the European coffeehouse. Seattle historian Walt Crowley hung out as a teenager in the mid-'60s on The Ave at the Eigerwand, which boasted one of the first espresso machines in town.

Far from the mainstream teen hangout that coffee bars have become, he says, "Going to a coffeehouse was a statement. You weren't hanging out at Dick's or Burger Master with the muscle-car guys after the football game or at the soda fountain like the glee club. It was about rebelling and smoking with eclectic, potentially dangerous people."

Emily, who started drinking coffee in eighth grade, and Allison say the local java joints are just a place to hang out and socialize. That's the point, say coffeehouse owners and managers.

"We get them in the morning before they head to school and then again after school," says Dawn Wilson, manager at Cup of Joe in Cedar Falls. "It's an alternative spot for them. They can't go to the bars, so this gives them a hangout. It's great having them here, because it keeps the place young."

A succession of coffeehouses across the nation has served generations of high schoolers, and at least one Seattle high school cafeteria features a popular coffee house outlet. They don't have to go to the coffee. Coffee has come to them.

Coffee also has come to kids in terms of taste. The new array of confectionery coffee drinks has lured teens' taste buds with the sweet help of whipped cream, caramel drizzle and chocolate shavings.

"I don't like black coffee," says Allison. "I like the sweet, creamy drinks. Vanilla cappuccino is my favorite."

"When I was young, the only choices were cream and sugar," Wilson says, laughing.

But is all that coffee good for teens? Some blame too much caffeine for a generation of overtired youngsters. But while research on middle-schoolers found that those who drank the most caffeine slept fewer hours and were sleepier in the daytime, it's not clear whether the stimulant is depriving kids of sleep or whether sleep-deprived kids are using the caffeine to self-medicate.

"Later at night, if I want to study, I might have a double shot latte," Emily explains, "but I'm not addicted to caffeine."

Experts say since most teens have just one or two espresso-based drinks a day, it's not enough to be concerned about in any case. For most kids, sugar and fat are a bigger deal. The 570 calories in a Starbucks' grande mocha malt frappuccino is comparable to the calorie load in a Big Mac.

And for the record, there's no data to support the claim of parents back in the day that coffee stunts growth.

"That's been around for generations," says Wilson. "I've been drinking coffee for years, and I still managed to grow pretty tall."