When Kim Russell started out as a special education teacher in San Francisco, she looked around the room and saw four kids in wheelchairs, another with a walker, others who were diagnosed as mentally retarded. One child had a neurological disorder called autism.

But that was seven years ago, still early in the story of a phenomenon now spanning the country. Today, almost all her students at Yick Wo Elementary School -- six out of seven -- are autistic.

And there are eight other classrooms in the district with a curriculum designed for children diagnosed with autism -- kids often set apart by their struggle to communicate, their social awkwardness, self-stimulating habits and obsessive interests.

The disorder has been reported in record numbers of kids nationwide. In California, it's the fastest growing segment in the state's developmental disability system.

"I have a parent who calls every week and says, 'Is there room yet? Is there room yet?' " said Russell. "I have to tell her, 'No, maybe next year.' "

But that already promises to be another bumper year -- 22 autistic preschool kids identified so far who will need kindergarten placement. And San Francisco, which now has an autism curriculum specialist and plans to add another one, is not alone.

The small Berryessa school district in San Jose, with about 8,000 students, has five classes of autistic kids this year and next fall will add a sixth. Specialists there have had so much practice, they've joined with parents to set up a nonprofit that has already trained more than 650 other teachers outside the district.

Donald Jolly, the head of special education in the Sunnyvale school district, didn't want to say which campus has a special class for kids with Asperger's syndrome, a milder relative of autism, because it's full and he doesn't want parents going to the school and "hunting around."

"We're starting to feel overwhelmed as a system," said Bob Baldo, executive director of the Association of Regional Center Agencies, which represents state treatment centers for the disabled. "The long-term implications are absolutely staggering as a state and as a nation."

The number of autistic clients at centers run by the state Department of Developmental Services (DDS) increased 273 percent from 1987 to 1998. In the four years since then, the cases have close to doubled again, and the latest quarterly numbers show they are continuing to explode at a record rate. Two- thirds are children under age 13.

And those figures don't even include the growing number of kids diagnosed with Asperger's syndrome. There is no centralized system for counting those cases, but school districts and therapists all say they're being inundated with Asperger's children as well.

MYSTERIOUS CAUSES

What parents find most alarming is that no one agrees on why more children are being diagnosed with these maladies. No one believes anymore, as they did until the 1960s, that autism is caused by "refrigerator mothers" who are distant and rejecting.

But newer theories abound, each with its own adamant proponents: a component in certain childhood vaccines, metabolic disturbances or environmental toxins. Or the increase might largely be due to earlier and different diagnostic criteria or a combinations of all these reasons. The only point of consensus is that heredity appears to play a role.

A state research team, using a $3.5 million grant from the federal Centers for Disease Prevention and Control, will spend five years investigating the avalanche of new cases at DDS regional centers in six Bay Area counties.

At the same time, the state has asked researchers at UC Davis to present legislators in June with their own report on the upsurge.

"It appears there are more kids now than there ever were, and it's not because everyone has seen 'Rain Man,' " said Dr. Robert Byrd, lead researcher on the study at the university's Medical Investigation of Neuro-Developmental Disorders Institute, founded by parents of autistic kids.

It was the 1988 Dustin Hoffman movie that gave most people their first look,

albeit a sentimental one, at the disorder.

The movie showed that someone with autism might be able to do things like memorize the phone book, play piano sonatas by heart or know the scientific name of every dinosaur, but be perplexed by simple questions such as "How are you?"

What "Rain Man" didn't show was the wide spectrum of symptoms and behaviors that continue to confound researchers. Some autistic kids are precocious early,

then lose skills; others never talk or talk obsessively. They're typically hypersensitive to outside stimulation and may learn to soothe themselves by clapping hands, humming or merely retreating into silence.

But autism was around long before "Rain Man." Leo Kanner, a child psychiatrist at Johns Hopkins University, described it in a 1943 paper that discussed the "fascinating peculiarities" he'd seen that didn't fit any existing categories. German researcher Hans Asperger published his research around the same time, but the disorder bearing his name wasn't widely used -- by parents or therapists -- until recently.

LONG WAITS, HIGH COSTS FOR HELP

With autism numbers soaring, parents have been scrambling for information and state-of-the-art therapies. They are finding months-long waiting lists for testing and therapy at clinics in Marin, Santa Clara and San Francisco counties.

Faced with delays, they are spending time and savings fighting for services they believe are crucial. Many families struggle to pay for a popular behavioral therapy pioneered by UCLA researcher Ivar Lovaas, a one-on-one treatment that can take up to 40 hours a week.

One Marin family has spent $100,000 a year on behavioral and other therapy and a home aide. A mother in San Jose acted as her son's full-time school aide until she could get funding for one at his school. A San Francisco couple say they've taken legal action against the school district at least three times to get their 10-year-old daughter into what they consider the right placement.

"Like every other family, we have to fight for what we get," said Eileen Attridge. "My husband is a lawyer, so he handled the hearings. He has an 'Esquire' after his name, and that's all that matters."

Deborah McKnight, interim director of special education in San Francisco, deals with anxious parents on a daily basis. Schools rely on diagnoses from their own testers, outside clinics or DDS regional placement centers to develop individual plans for autistic kids.

The regional centers and school districts will pay for treatment based on the evaluation's recommendations. But those sometimes don't match what parents think is best, particularly in light of what many experts believe is important -- early treatment before kids are school-age.

"People do research on the Internet and they are experts on what's available," said Santi Rogers, head of the San Andreas Regional Center in San Jose, one of 21 centers statewide that provide services, testing and referral. "There may be Brand X, Y and Z and they want X. We're not cynical, but we have to understand what's out there and what will work."

There is a three-month wait for testing at Langley Porter Psychiatric Institute's autism clinic at UCSF. By the time parents get there, their children may have been to other doctors and specialists. Dr. Bryna Siegel, head of the clinic and author of a well-known resource book, "The World of the Autistic Child," is part of a team that evaluates kids.

CHANGING GUIDELINES, LABELS

She doesn't believe what she's seeing is a true epidemic. Rather, she says, kids are getting tested and diagnosed earlier using newer guidelines in the Diagnostic and Statistical Manual -- the gold standard of psychiatric diagnosing. The manual, revised in 1987, describes 16 specific areas of development to rate for autism.

But many parents don't think that's the whole reason. Rick Rollens, who co- founded the MIND Institute, said his son Russell began life in 1991 as a normal robust infant, then started slipping into autism after a routine vaccination at 7 months. The condition worsened later when Russell suffered severe digestive problems after his first measles, mumps and rubella shot.

After taking Russell to countless doctors, Rollens became convinced his son had vaccine-induced autism. The co-founder of Families for Early Autism Treatment, which now has an online newsletter reaching 20,000 people, Rollens said his story "is not unique," although he thinks there is probably more than one cause of autism.

Siegel said the vaccine theory is hard to prove because autistic children often learn to walk and talk normally, only to lose those skills in the first few years of life.

Many of the children she sees have a collection of symptoms, some of them fitting autism and others resembling attention-deficit or obsessive-compulsive disorders or mental retardation, she said. Twenty years ago, they might have received different primary diagnoses, she said.

"As far as social attitudes, autism is perceived with less stigma than mental retardation," she said. "When I started running an autism clinic in 1983, the residents I was training didn't want to tell parents their kid was autistic, but it was OK to tell them the kid was retarded. Now residents do just the opposite."

Sometimes, Siegel said, parents want the autism diagnosis because they feel their children will get better, earlier services.

"What sounds good about mental retardation?" she said. "Parents think that a mentally retarded kid can't learn anything, which isn't true."

Siegel thinks labels are less important than the treatment plan a child gets. Often symptoms don't fit a pattern and need a variety of therapies. But whatever the diagnosis, she knows how hard it is for parents.

"You don't expect to have a kid with a handicap," said Tobie Shapiro of Berkeley, whose 15-year-old son, Meyshe, taught himself to read and write at age 2 but didn't learn to talk. "I didn't know anything about a whole variety of things that can go wrong."

Shapiro, like many researchers and parents, believes genetics play a role in autism. It's one of the theories that the CDC-sponsored local study will investigate.

Researchers and parents alike have noted that the same traits that make for engineering or computer whizzes -- brilliance in one specific area such as spatial or math reasoning and intense inward focus -- show up in people with autism.

"I've seen a lot of physicists and mathematicians who are on the (autism) spectrum," said Shapiro.

Shapiro, in frustration, has turned to home-schooling her son, but other families are still clamoring for school help. And districts are finding that training teachers and assembling resources to deal with escalating numbers of autistic kids is a laborious, expensive process.

LEARNING THROUGH ROUTINES

San Francisco -- where younger kids are in autistic-focused classrooms, regular special education and mainstream classes -- is scrambling to start classes for kids beyond elementary school.

Russell, who has been to training classes and seminars, relies on predictable, set routines at Yick Wo Elementary. Each morning students take their name tags from a placard near the front door and place them on an activity board in the front of the room, moving them to different work stations during the day.

And each kid has a book of pictures that are attached to pages with Velcro. They use the picture clues to work on language, pointing to what they want -- a song, a snack or a toy -- before saying it.

Russell also uses behavioral training, a set of well-defined small tasks, with rewards for completing them. One girl has pictures of a doll and a favorite book at her desk, rewards she'll get to pick when she finishes alphabet work.

All students get individual speech therapy and spend time playing with kids from regular classes in supervised play groups.

Some, like Max Dycus, 7, get other individual treatment. His education plan calls for music therapy an hour a week. In a small room, the therapist sings to encourage Max to speak and look him in the eye.

Max, who can zip around the Internet in search of Thomas the Tank engine sites and use a remote control like a pro, has little interest in socializing. But he smiles ecstatically when he gets a chance to jump to music on a small trampoline.

"I think we're on the right road," said his mother, Melinda Lee. "We've had good luck, but it's not really luck. It's been hours and hours on the telephone. My husband practically gave up his job for a year."

One day recently, a girl in the class was happily playing in a plastic playhouse when she stepped in a puddle and began to shriek and wave her arms. An aide calmly walked over, took the girl's hand and said, "Tell me sock off, sock off."

The girl sat down on a bench, held out her foot and repeated the phrase. The aide removed the sock and the girl stopped crying, resolution of one small problem, part of what will be many that day.

"I have visions for these kids, where they'll be in 10 or 15 years," said Russell, ever hopeful, though she knows there is no recognized cure for autism.

"One loves to skate, and she'll be an Olympic gold medalist. One will be a book reviewer. One will work in a store because she loves shopping bags, especially the handles. One will be at Microsoft. He'll be rich and maybe he'll say, "I want to go back and take care of my teacher.' "