Young people around the country love America Online, zipping instant messages back and forth and using it to explore the Web. But yesterday, with a single e-mail, AOL sent a wave of surprise and anger through its biggest youth fan base -- about 450 AOL "volunteers" under age 18 -- by firing them from their jobs.

These kids, many of whom went through 30-some hours of training, spend hours every week on such jobs as monitoring chat rooms for improper language or other violations and answering questions from fellow AOL users. AOL contends that it wants people who are more mature in these functions.

Josh Kahn, 15, of Miami is so devastated he said he's going to come to Washington to picket in front of AOL's Dulles headquarters later this month. "All my friends have been dismissed," said Kahn, who has been an AOL volunteer for two years. "This is our little area and they took it away from us."

"AOL has decided to limit eligibility in the Community Leaders Program to AOL members eighteen years of age and older," says the July 22 e-mail signed by Berl Jones, senior manager of AOL's Community Leaders Organization.

Since its inception, AOL -- like many online services -- has used volunteers to watch discussion groups, answer questions and alert AOL staff to potential problems. In return, the volunteers receive a free account, and sometimes access to certain areas not open to the public. AOL says it has a total of 14,000 of these "community leader" volunteers.

The showing of the door to the under-18s comes at a time when volunteerism in general at AOL is a controversial issue. In May, two adult former volunteers filed a lawsuit in a federal court in Manhattan against AOL, saying that the company's practices violate the Fair Labor Standards Act, and that AOL owes them compensation.

Some analysts think the suit, depending on how it is resolved, could change practices of volunteerism all over the Internet.

Some analysts have suggested that AOL's jettisoning of the below-18 volunteers may be motivated by concerns that their work violates child labor laws, but AOL denies there is any connection.

Maia Howell, 17, is so furious at AOL that she's gathering names for a petition of protest. "I don't know if this is a power trip or what," Howell said. She plans to send the petition directly to Steve Case, AOL's chief executive.

Howell, who lives in Anoka, Minn., said she went through about 40 hours of training to become a volunteer. "They totally screwed up," she said.

"I feel like I wasted my time. They allowed us to sign up for this." But, like other teenagers interviewed for this article, Howell said the second she turns 18, she'll be back.

Josh Kahn's father, Rabbi Jeffrey Kahn, said he thinks AOL has a monopoly over young people who want to get on the Internet. "It's really unfortunate for AOL to treat them this way," he said.

Kids and parents were especially outraged yesterday because AOL, which has 17 million users, promotes itself as a family-friendly service, and certainly benefits financially from its enormous popularity with children.

AOL spokesman Rich D'Amato said the service announced last fall that it would not take any more under-18 volunteers, except in certain sections geared particularly toward kids, though it would grandfather in current young volunteers.

The new policy takes effect Aug. 23, when the 400-500 remaining under-18 volunteers must delete their community leader screen names. If they decide to stay with the service, they'll start getting charged just like regular subscribers a month or two later.

D'Amato said that paid AOL employees, who have more training, will monitor chat rooms and act as guides for AOL's youthful sections.

AOL will still let kids over 16 participate in a "peer tutoring program," where teens help other teens with schoolwork. But this week it also increased that age requirement from 14 to 16. "We understand that kids want to participate in the community," D'Amato said. "But it does require a certain level of maturity."

Kelly Hallissey of Greensboro, N.C., one of the former adult volunteers who is suing AOL, said she thought the kids "got shown the door in a nasty way."

Hallissey, who runs a Web site at www.observers.net, has become an organizer of disenfranchised former AOLers, paid and unpaid.

John, 16, of California, who didn't want to give his last name, said he was furious to lose his volunteer status and baffled as to why. "AOL is trying to make us go quietly," he said. John said the AOL kids could strike back at the company. "They have the training, they have the access, and they have the motive to be troublemakers now," he said.