Daniel Jankowski was 18 months old when his parents began noticing his development was remarkably different from that of his two older sisters.

``He didn't respond when we called his name, and he played with his toys in an unusual way,'' said Ann Jankowski, Daniel's mom. ``But it was his lack of language which really caused us concern.''

Ann and Michael Jankowski scheduled an appointment with Daniel's pediatrician. The doctor assured the worried parents their son was fine.

``He just said boys develop slower than girls and told us not to worry about a thing,'' Ann Jankowski recalled.

But the parents' instincts told them different. Months later, at the suggestion of a friend whose son had autism, the Jankowskis took Daniel for another examination - this time with a neurological expert.

Daniel was diagnosed with autism.

The news of such a diagnosis would seem enough to send any parent reeling. But the Jankowskis and others like them say becoming an educated, grounded advocate is the best defense any parent could give their child.

Parents say the need for such a position emerges early on.

``Nobody knows your child better than you do,'' said Cathy Silbert, whose 11-year-old son, Zacharia, has autism.

Silbert noted that like the Jankowskis' doctor, many family pediatricians misdiagnose autism.

``Much of the improved diagnosis and treatments are because of pushy parents who insist on getting the best care for their kids,'' she said.

Autism is the third most common developmental disorder in the United States and is increasing at a rate of 10 percent to 17 percent each year, according to a report by the Autism Society of America.

More common than Down syndrome, cystic fibrosis, multiple sclerosis or childhood cancer, autism includes symptoms of impaired social interaction and communication skills; restricted and repetitive behaviors; sensitivity to light, noise or other stimuli; temper tantrums; self-injury; and impulsiveness.

For Cathy and Jerry Silbert, that translated into a boy so afraid of crowds that he would vomit when surrounded by strangers. Unable to express himself with words, Zacharia must rely on sign language and picture cards to communicate with his parents.

The Jankowskis, whose son is now 7, have altered their lifestyle to ensure Daniel is always as comfortable as possible. That means, among other things, a two-hour commute to and from school each day.

``We found a school that best matched Daniel's needs, and we couldn't deny him simply because it was more than 60 miles away,'' Ann Jankowski said.

Family activities such as eating out and Disney vacations are out of the question, because Daniel cannot stand a lot of stimulation.

It's a tough balancing act for the family of six, she said. Of four siblings, Daniel is the only one with autism.

Autism, a neurological disorder, occurs in one in 250 births, and doesn't normally appear until early childhood, the autism society reports.

The Jankowskis admit it is a lot for any parent to take in.

``Sure, you're going to have feelings of hurt, fear and confusion,'' Ann Jankowski said.

``But you have to take a step back, take it one day at a time and learn all you can about the disorder.''

For most parents, that means connecting with other families dealing with autism.

``The best thing any parent can do is to leave the doctor's office, go straight for the Yellow Pages and look for support groups,'' said Ann Jankowski. ``It may sound like a small thing when you compare it to all that lies ahead of you, but it really is the best anchor.''

Most communities have a local branch of the Association for Retarded Citizens that provides information about special education options, governmental programs, autism support networks and other important services, according to Jerry Silbert, who is also the president of the Massachusetts chapter of the Autism Society of America.

The Department of Public Health also is an important resource that many parents overlook at first, he said.

Silbert said such agencies are invaluable to parents just learning of their child's disorder because they provide a wealth of information about early intervention services, which is the cornerstone of a child's success.

``These kids can do great with early intervention,'' Jerry Silbert said. ``But the key is that parents have to know what's available, and they have to provide their child every opportunity.''

Parents have been busy making their voices heard.

Earlier this month, as part of Autism Awareness Month, parents statewide talked with legislators on the need for a study on how the rate of autism in Massachusetts compares with other states.

Laurie Flutie, mother of an 11-year-old son with autism and wife of football great Doug Flutie, said parents have to speak up on behalf of their children, but the state needs to understand the scope of the problem to make the biggest impact on those families.

``We know firsthand what it's like to have a child with autism and the struggle families go through to coordinate the services our kids need,'' said Flutie.

Rep. Barbara L'Italien (D-Andover), a parent of a child with Asperger's syndrome, a spectrum disorder of autism, said there is now a great need for parental involvement on a governmental level because of recent budget cuts.

Parents of autistic children said they fear the cuts in special education may cause local programs for children with autism to disappear.

``I don't want to see these kids go without,'' L'Italien said.