In their complaints to the Labor Department, the former volunteers do not make explicit demands for back pay. The issue, they said, is to publicize the situation and to change the way the on-line service uses unpaid labor.

''Some are filing for revenge, some are filing to stop AOL from abusing others, some simply want their AOL accounts returned to them,'' said Kelly Hallissey, a former volunteer who lives in Greensboro, N.C. ''I'm filing to support others' allegations and also to object to how AOL has treated myself and many others.''

Under the Fair Labor Standards Act, a person must be compensated for time spent at job-related activities that benefit the employer, regardless of how the job is classified. There is a difference between volunteering for a charitable cause and volunteering to perform work that is critical to a company's business, said Jeffrey Chamberlain, an employment lawyer based in Albany who is not involved in the AOL dispute.

In a claim like the one made by the former AOL volunteers, Mr. Chamberlain said: ''The more it looks like a real job, the less likely it is to be deemed volunteer. The kinds of things they are describing would make lawyers' bells go off.''

But Ms. Brackbill defended the volunteer program, saying it was a formalization of contributions that AOL subscribers have made to the service since it began in 1985. ''It's an organic thing that sprouted from what people love to do on line,'' she said. ''Community and participation are the DNA of the Internet.''

AOL is not the only on-line company to use volunteers. Many Internet companies that offer community features rely on members to enforce standards and to contribute to the community in some fashion.

For instance, Ivillage, an on-line women's network, uses more than 1,000 volunteers to manage message boards and chat communities.