PROVIDED they're old enough to keep the mouse out of their mouths, there's something for nearly every child in Wonderland, at the Web site of Sony Wonder, the entertainment company's children's label. Wonderland bills itself as "a safe place to play and grow."

The Wonderland site, far from being an anomaly, is typical of many Web pages geared toward youngsters. While many parents are worried that their children may be exposed to pornography on the Web, children are far more likely to spend time looking at something else altogether: advertising.

Certainly television and other media have long been used to sell to children, but advertising on the Web is virtually unrestricted. There are voluntary advertising guidelines for the Web and traditional media set by the Children's Advertising Review Unit, an organization operated by the Council of Better Business Bureaus and financed by advertisers.

PROVIDED they're old enough to keep the mouse out of their mouths, there's something for nearly every child in Wonderland, at the Web site of Sony Wonder, the entertainment company's children's label. Wonderland bills itself as "a safe place to play and grow."

Wonderland's Wading Pool ("The perfect place for 2- to 3-year-olds to get their feet wet in the World Wide Web") offers toddlers the chance to play Click-a-Part Choo Choo, an animated computer game "inspired," Sony Wonder carefully notes, by a John Denver children's CD the company distributes.

For 4- to 6-year-olds, there are slightly more complex games that are mostly inspired by videos released by Sony Wonder, like William Wegman's Mother Goose.

Recently, older children who might have been interested in a Barbie album called Beyond Pink could have won a prize for filling out a long questionnaire to see if they were a "Beyond Pink kind of girl."

The Wonderland site, far from being an anomaly, is typical of many Web pages geared toward youngsters. While many parents are worried that their children may be exposed to pornography on the Web, children are far more likely to spend time looking at something else altogether: advertising.

The Web has become an irresistible tool for many marketers looking for ways to capture some of the estimated $130 million a year children spend as well as the $500 million in purchases they influence. One of the chief methods marketers use is to combine advertising and interactive content until, as on the Wonderland site, the line between the two is almost obliterated.

So far, the use of the Web to sell to children has attracted little of the attention that television advertising has attracted over the years. But a small number of critics warn that by focusing almost exclusively on the dangers of online sex and violence, parents may be missing an arguably more widespread problem.

"It is overwhelming," said Dr. Michael Brody, a child psychiatrist in Washington who studies the impact of advertising on children. "In general in our society, content and advertising have become blurred. But on the Internet it's a blitz."

Many advertising-heavy sites for children are operated by companies like toy and cereal makers that have traditionallyaimed at children or by popular entertainment companies like Sony and Nickelodeon. But sites that are billed as educational, like the PBS Kids pages, the Knowledge Adventure Encyclopedia and the Kids' Almanac, also feature advertising, usually in the form of click-on advertisements.

Even companies unrelated to children's products, like the oil giant Chevron, have Web sites for youngsters. The Chevron site features games, toys, videos and homework sections touting the importance of - what else? - the oil industry.

Relatively few sites aimed at children directly offer merchandise for sale. One such site is a popular one offered by Nickelodeon, which links directly to an online toy store called Red Rocket. But many companies are indirect, offering attractive, free entertainment to build a profile for their products and, in some cases, to gather marketing data.

"In some ways it's as if companies are entering our homes and picking the brains of our children for commercial purposes," said Dr. Kathryn Montgomery, president of the Center for Media Education, a nonprofit lobbying group in Washington.

Certainly television and other media have long been used to sell to children, but advertising on the Web is virtually unrestricted. There are voluntary advertising guidelines for the Web and traditional media set by the Children's Advertising Review Unit, an organization operated by the Council of Better Business Bureaus and financed by advertisers.

While the voluntary rules for Internet advertisements are generally the same as the voluntary guidelines adopted by major television networks for advertising in their medium, there are some significant differences.

For example, guidelines forcing a clear separation between content and advertising on television do not apply to the Web. And the ban on characters, real or animated, acting both as content and pitchmen does not affect the Internet.

Tony the Tiger can act as a host on the Kellogg's site, Planet K, whereas no television network would be allowed to accept a cartoon show based on the Frosted Flakes mascot (except in the unlikely case that Tony the Tiger was the host of a show that was not sponsored by Frosted Flakes).

Elizabeth Lascoutx, a vice president of the Council of Better Business Bureaus and director of the Children's Advertising Review Unit, said the standards simply reflected the differences between the media. "It's easy to make the separation on television," she said. "You can say, `We'll be back in a minute.' "

Not surprisingly, the most intensive research into the Internet's power as a means of selling to children has been conducted by the advertising industry. Kid Connection, a unit of the agency Saatchi & Saatchi, has twice commissioned studies from cultural anthropologists and clinical psychologists, what the company refers to as "psychocultural youth research."

The most recent study involved clinical psychologists interviewing 84 young people between the ages of 6 and 20 and then analyzing their dreams, drawings and reactions to symbols. The anthropologists camped out in houses watching other children use the Net for about 500 hours. As well, Saatchi & Saatchi has a panel of about 300 children it communicates with regularly by e-mail.

"One of the really critical findings of the study is how rich digital media are in the lives of children," said Johann Wachs, vice president for strategic planning at Kid Connection. "They provide an enormous developmental push. It's bound to have a major impact on kids."

Much of that impact is determined by how the approach is made. Based on its research, Wachs said that Saatchi & Saatchi had learned that merging content and advertising was the only effective way to reach children from moderately affluent families.

"This is a generation with a very ambivalent attitude about advertising," Wachs said. "They know and perceive of themselves as a target market. But they are actually very open to advertising and enjoying being courted by advertisers if it's something that adds value by being entertaining."

The practical results of Saatchi & Saatchi's research can be seen at You Rule School, a game site developed by the agency to promote cereals and snack foods made by General Mills. Once visitors register and get a personal locker number, they have the option of playing a number of elaborate games, like the Fruity Obstacle Course, where a bug-eyed animated character crosses a cavern in a cartoon version of a General Mills Fruit Roll Ups factory.

It is a memory game that involves building a bridge by matching Fruit Roll-Ups coming off an assembly line with their appropriately shaped packages. Users can also gobble a yard-long maze of General Mills Fruit by the Foot and blow off steam by stomping on some General Mills Fruit Gushers before rounding out their day swinging Tarzan-style from a General Mills Fruit String Thing.

What concerns many critics is that the children being lured into attractive, multimedia corporate Web sites are unwittingly being used for market research.

For example, children who want to earn points that can be exchanged for free merchandise on Kidscom.com - a Milwaukee-based, advertising-supported site with games and other features - must answer 21 questions. Several focus on the family's computer equipment, hobbies and favorite activities.

Lane Beauchamp, general manager of Circle 1 Network, the company that owns Kidscom, said that advertisers could get only aggregated data about users of the site; no personal information about a specific child is ever offered. That information is used in-house to judge a user's technical capabilities and to match children in an optional e-mail pen pal service.

But some questions appear to have psychological overtones. Among other things, users who want to collect Loot Locker points are asked to give their career dreams and to complete the statement, "If I could shift into anything I wanted to be, I would change into . . . " The suggested answers are a bird, a fish, an animal or a plant.

The Federal Trade Commission is developing rules to bring into effect the Children's On-Line Privacy Protection Act, passed by Congress last year, which is intended to protect the privacy of Web- surfing children.

Child advocacy groups are not calling for an end to Web advertising aimed at children. But Montgomery does not agree that the nature of the Web should necessarily dictate policies for children.

"The Web is something we as a society have created," she said, "and it's not locked in stone that commercials have to be integrated into content. Something is wrong with this picture." She said she would prefer to see some commercial-free Web areas set aside for children, "just as we have public playgrounds in the real world."

Some children's sites with advertising are trying to adhere to limits. Kevin Dando, associate director for education and online communications for the Public Broadcasting System, said the PBS pages designed for children would not be topped by banner advertisements - unlike the pages aimed at adults.

PBS has also instituted "bridge" pages between its own site and the rest of the Web so surfers who click on a vivid blue logo for Rice Krispies that lies at the feet of the four Teletubbies is not immediately whisked away to Kellogg's Planet K.

The bridge pages issue a warning that the user is about to leave PBS and offers the option of heading back rather than plunging into the cyber cereal world. "As well as being a pause, we want to use the bridge page as a place where children learn something," Dando said. The Nickelodeon site has adopted a similar system.

For Wachs at Saatchi & Saatchi, parents' fears about Web advertising, like many issues related to the Net, are a product of ignorance, born of the concern that "the kids are doing something they don't understand and therefore it may be dangerous."

He suggested that intermediate steps like bridge pages would not slow the merger of advertising and content on the Web. On the Internet, he said, "advertising is going to develop more and more into entertainment content; advertisers have to play along."

Where kids are looking

Here are the Web sites that had the largest proportion of users between the ages of two and 11 in December, according to Media Metrix, an Internet-traffic measuring service. The information is based on a telephone and e-mail survey of 40,000 people in the United States.

Tips for parents

Advertisers covet the youth market and the $130 million in buying power it represents. Here are some ways parents can deal with Internet advertising aimed at their children.

Remember that the Web is not television: "Not all advertisements on the Internet look like commercials on TV," said Jane Tallim, the education coordinator for the Media Awareness Network. "When you play games with product spokescharacters or color and download their pictures, this is advertising."

Talk to your children about advertising: "Kids need to know they're being seduced, but you don't have to do it in a harsh way," said Dr. Michael Brody, a child psychiatrist. "It's like dealing with sex in some ways."

Limit exposure to children under 7: Many experts believe that until age 7, children cannot distinguish between advertising and content. "I wouldn't let a child under 7 on the Internet alone any more than I'd let them go to the 7-Eleven alone," said Anne Taylor, co-director of the Media Awareness Network.

Keep an eye on the screen: Parents should place household computers in family rooms and other common areas where they can monitor their children's Web habits.

Teach children not to give out personal information: Both advertisers and critics agree about this issue. "There is a hidden cost when companies offer you free prizes, invite you to join a club or ask you to register with their site before playing games," Tallim said. "That cost is private information about you and your family."

Elizabeth Lascoutx, director of the Children's Advertising Review Unit, an advertiser-financed agency that monitors adherence to voluntary guidelines, backs a formal process by which parents would have to give permission - by phone, e-mail, fax or letter - before children could turn over details that might allow others to contact them. But Lascoutx acknowledged that the ability of Web sites to collect data outstrips their power to notify parents. "I wish they'd hurry up and give us a real neat technology to deal with that," she said.

Be wary of chat rooms: If your child does go into a chat room, insist on the use of a nickname. "Remember that companies or others might be collecting information or guiding the discussion," Tallim said.

Credit: New York Times