By Rieva Lesonsky

We’ve talked about this surprisingly powerful demographic before, but the influence this group has is growing, so it’s time to take a deeper look. Here’s how Adweek magazine put it: “She wants to be anything but the age she is, always looking toward the future, is ambitious, opinionated, influential-and knows more about technology than you ever will.”

“She is 9 years old. She is a tween.”

Tweens (both boys and girls) range, depending on who’s defining them, in age from 8 to 12 (some say tweendom starts at age 9). As a group they spend an estimated $30 billion of their own money yearly, and have “pester power” over another $150 billion spent on them by others (mainly their parents).

In a new article, Adweek talks about the efforts of some of the nation’s biggest marketers, including Walmart, Target, Chobani yogurt and Mattel, are making to target these kids.

There are opportunities aplenty in this market. Research firm NPD Group shows tween girls are using almost twice as much mascara and eyeliner as they did only two years ago. For this group, also think clothes that are decidedly more grown-up than you remember dressing in when you were this age, fashion accessories and home décor items.

Tweens are part of the digital native crowd, and preternaturally understand electronic devices of all types. Admit it, how many of you have handed your smartphone or digital camera to a kid and asked them to explain something to you? I’ve done it on more than a few occasions.  They want (and get) their own smartphones, digital cameras and, yes, even iPads.

Don Tapscott, author of Growing Up Digital: The Rise of the Net Generation (affiliate link), told Adweek that “most of what we know about marketing to the demo is ‘wrong or is becoming wrong’.” He explains, “They don’t want product, they want experiences.” If you’re marketing to this group, Tapscott adds, it’s important to “engage them.”

You do need to be a little cautious with this market. Tweens are notoriously fickle, and can desert your brand as quickly as they embraced it.