They agonize over price. They're thoughtful, not impulsive. They arrive at the mall with information and purpose. They actually care about what their parents would think about those micro shorts.

They are teenage girls, and this is how they shop.

It wasn't what we expected to find when we spent a recent Saturday afternoon shopping at the Washington area's largest mall, Tysons Corner Center in Virginia, with a horde of teens.

This is a generation often considered indulged, equipped with cellphones and credit cards at an early age. Teens' purchasing power is enormous. Last year, they rang up $179 billion in sales, according to Teen Research Unlimited. But they can be a fickle demographic, helping send sales at a retailer soaring one season only to abandon it the next for another with fresher merchandise.

We were curious: What are the small decisions, the information and inclinations at work as teens shop? When do they stop and buy, when do they move on? We called parent-teacher associations, the Girl Scout Council of the Nation's Capital and the Boys & Girls Club of Greater Washington, and posted a notice on the Washington Post's Web site seeking volunteers to shop, just as they normally would, with their own money and friends.

We wanted to get inside their heads.

Sixty-one teens in grades seven to 11 from all over the region, mostly from public schools, responded to our call. They came to Tysons in jeans, flip-flops, dresses, head scarves, gym shorts and braces. Some shopped with their parents, others with friends. They came armed with carefully saved weekly allowances, baby-sitting money, birthday gift cards and, yes, their parents' credit cards.

Although several boys said they would come, only one did. Apparently, boys are not recreational shoppers. This was a girl thing.

We equipped the shoppers with paper and pen, asking them to record their movements through the mall, writing down every stop and dollar spent. Some wore microphones to record their conversations and observations. Seven reporters trailed them. Five videographers and four photographers documented their journeys. We polled them on their favorite stores, the must-have items at school and how much they would pay for jeans. (Answer: Not as much as you think.)

They wound their way through the mall in twos or threes, save for the five members of Girl Scout Troop 1016 from Fairfax, Va.

They often crossed paths — overwhelmingly shopping at a handful of retailers over and over again — and frequently text messaged or called their vast social networks for approval or advice.

"Don't get solid colors — that's boring," warned the voice on the other end of the cell phone when Billie McCain, 16, called a friend for emergency fashion advice in the middle of Macy's. "And no sweaters because you wear sweaters too much. Get a blazer or a jacket."

They visited American Eagle, Hollister, Forever 21, Urban Outfitters, Abercrombie & Fitch, Delia's and Old Navy most often. One girl bought nothing; others spent more than $100. All told, they spent $3,764.85.

"I go to stores I know will have my style," said Kiara Hill, 13, pointing out that her style is subject to refinement. "Forever 21 surprised me. It didn't used to be my style. Today, I liked it a lot. It's my favorite store now."

Before the first hour was up, Grace Ellison, 15, a bassist and singer in a punk rock band, declared, "I love Wet Seal."

Not Gretchen Heberling, 16. "Wet Seal disgusts me," she said. "They're trying to force trends."

For most of them, price was a major consideration. They looked for value and often took prices they considered high as a personal insult. Some pointed out they prefer to shop with their parents because their wallets are fatter.

Sixteen-year-old Whitley Gaffney, who has a $40 monthly allowance and describes herself as one of the "preppy dressy" kids, sees it this way: Clothes introduce her to people around her.

"I want them to know a little bit of who I am," she says. "And I'm proud of it."