Startling news this week from the world of preschools: 2-, 3- and 4- year-old children are expelled from school at a rate three times greater than students in kindergarten through 12th grade.

The findings were released in a Yale University study that looked at publicly funded child care centers in the 40 states, including California, that offer such programs. Preschool expulsions in California mirrored the results of the nationwide survey.

The study did not ask respondents about the reasons for expulsions, but project leader Walter S. Gilliam told the New York Times that aggressive behavior toward teachers or fellow students, recurring acts of defiance or a violation of zero-tolerance policies regarding violent behavior could bring an expulsion.

For child care providers in the Bay Area, the report doesn't raise suspicions about their own students as much as it confirms that many of the region's child care centers are at least a decade ahead of their counterparts in other states.

Mental-health intervention for preschoolers with behavioral problems has been part of the landscape here for nearly two decades.

"Kids are coming into group settings unprepared for the kinds of stimulation and encounters they experience with other children, the environment and staff,'' said Grace Manning-Orenstein, a psychologist and the director of The Link to Children, known as TLC. The 10-year-old mental health intervention service contracts with child care centers in Oakland, Berkeley, Castro Valley, Emeryville and Pleasanton.

"The expulsion situation we've known about forever,'' Orenstein added. "At age 3, you are more likely to get the benefit of the doubt, but by 4 or 5 (the centers) just don't want to put up with you anymore.''

TLC sets up temporary offices in the centers and engages children who've exhibited antisocial or aggressive behavior in play therapy in an effort to address the roots of the problem. About 18 percent of the students at the nine centers her group serves have been evaluated as at-risk kids who exhibit the kinds of anti-social behavior that raise a red flag with teachers, she said.

"We give kids lots of objects on a shelf -- animals, farmers, Indians, trees and rocks -- and kids pick from them and create their world,'' she explained. "We watch them do it and draw information from it.''

But there are various reasons for children acting out, and there is plenty of blame to be spread around to the adults in the child's life.

Sometimes the issue is simply the lack of parental involvement in a child's life or a chaotic situation at home. Sometimes the child care providers don't know enough about child development to adjust their expectations of conduct.

Betty Cohen, the director of Bananas, an East Bay child care referral service, runs a hot line for preschool teachers, and some of the questions she's fielded illustrate the lack of understanding in child development that creates situations that the child can't handle.

"I got a call from a teacher who wanted her 2-year-old students to sit in a circle, and that's fine for a 4-year-old, but a 2-year-old won't do it,'' she said. "You want them to explore and be curious; that's how they learn about their world. You don't want them to sit still, do nothing and learn by rote.''

Beyond the behavioral difficulties that result in expulsion, there is often pressure from the parents of the children who are victimized by the class kicker, scratcher or biter. In other words, the threat of litigation against a teacher or institution can be a factor in the expulsion of a student.

"I think that teachers feel there will be trouble if they allow a child who's bothering others to remain in class,'' said Liisa Hale, director of the Association of Children's Service, a state-funded private child care center in Oakland. "Someone whose livelihood depends on caring for a dozen children is dependent on the income.''

But child care providers say the worst may be yet to come for kids whose parents have shuttled them from center to center, never revealing the behavioral problems that prompted the moves.

By the time the children are ready for kindergarten, the failed attempts to participate in group behavior can linger. Coupled with the disappointment from adults whom the kids rely on for approval and self-esteem, preschool expulsion can lay the groundwork for ongoing trouble.

"It's bad enough that a 2-year-old is kicked out of a single child care center, but what we've seen anecdotally is that it's those children who go through two or three programs who wind up not feeling very good about themselves,'' said Kadija Johnston, director of Infant Parent Program at UCSF, an 18-year program and one of the first of its kind in the nation.

"It can be the beginning of a child's internal view of who they are and what the world has to offer them,'' she said. "They are children, and they have nothing to compare that with.''