I thought I could win the battle for my child's brain.

Until she was about 4 years old, Parker, a tall girl with sandy brown hair and enormous blue eyes, was largely shielded from brands and the plethora of screens used to spread their fairy dust. At home, she had no access to cable TV and viewed only parent-approved DVDs and sporadic bouts of PBS Kids. She didn't know how to use the remote control, had no access to video games, and knew only the kind of web made by spiders. Her favorite activities were painting, playing tag, picking tomatoes, and dancing when no one was looking. She remained clueless about the Kids' Choice Awards, Radio Disney, FrootLoops.com, and avatars. I realize that in the eyes of some parents, this makes me a little uptight.

In our daughter's presence, my wife and I would mute commercials, spell out the names of chain stores, and refer to Ronald McDonald as "the clown." But we cannot keep our little girl in a marketing-free bubble. Thanks to an aunt, Hello Kitty has become her starter Abercrombie & Fitch. Thanks to her grandparents-- OK, and a few times her dad--she has half a dozen of the 40,000 items adorned with the Disney princesses. And we have watched as the alien baby of tween marketing has grown in her child-sized belly. Before she had either seen or heard the Jonas Brothers, for instance, she spontaneously declared the group to be a good band. We once found a pair of 3-D glasses in her cubby at preschool, kid swag promoting the Hannah Montana section at Wal-Mart. Did I tell you she has grown-up consumer preferences (she wants a convertible like Barbie's) and appearance issues (she wants blond hair)? Did I mention she had them when she was 4?

Well, I'm not uptight, OK, and I don't live off the grid or in a yurt. I'm just a dad who thinks that the business of selling things to kids is out of control. Researchers have linked this marketing phenomenon with a host of negative consequences. Childhood obesity and the sexualization of girls garner the headlines, but these issues are simply symptoms of a larger illness: conflicts with parents, psychological distress, indifference toward others, and a disregard for the world itself. Exposing a child to high levels of marketing, in other words, is a great way to make a child unhappy, unsuccessful, and unlikable.

Most of us think of marketing as ads, but with shows having become toys having become brands, I look at the most innocent stuffed bear with suspicion. "Even Sesame Street has an army of Elmo dolls out there now," says Michael Rich, M. D., director of the Center on Media and Child Health at Children's Hospital in Boston. "For a child, these products are a connection to Sesame Street. The relationship they have developed with the program is leveraged to make them desire that brand. They're just learning to be consumers, [which carries] a mentality that says, 'If only I can have that, I will be happy.'"

Advertising has always been with us, but there's no comparing your memories of 30-second ads with the 24/7, 360-degree, multimedia Manhattan Project now under way to own your children's brains. In the past 25 years, marketing to children has grown from $100 million worth of holiday-time ads to a $17 billion effort to seed brands and licensed characters into every corner of children's lives. With the convergence of technology that connects televisions, cellphones, and the web, kid-brand gurus have developed an unprecedented array of Trojan-horse methods to enter your kid's head and capture his mind. What's at stake is more than a few dollars; it's the internal emotional adventure of childhood itself.