More than one million Americans are autistic. It's the fastest growing developmental disability estimated at one in 166 births a year. Much has been reported on autistic youth and as we come to terms with this trend among children, many wonder: what happens when all these children grow up?

ABC News correspondent John Donvan and producer Caren Zucker offer an in-depth look at adult autism through the experiences of two autistic adults and their families in “A Place in the World” to be aired this Friday October 7 on ABC News “Nightline” at 11:35pm. Both Mr. Donvan and Ms. Zucker have family members with autism.

As Mr. Donvan reports, a significant challenge facing these families is establishing enduring support for their children to last through adulthood and life. Jim and Jen Hoppe of Wycoff, NJ, whose 21-year-old daughter Jamie is profoundly autistic, helped develop a school, where Jamie made enormous progress for 16 years. But, as Jen explains, there was no place for Jamie to go as an adult: “Nobody knows what the plan is. The number of people with autism has just overwhelmed everyone. …there is no plan… we have to make a plan.”

For the parents of Paul DiSavino, who is 36 and autistic, the concern now is what will happen to their son after they've gone. As Mr. Donvan reports, their current solution is a group home, but the alternative would be unbearable. Says Paul's mother, Marlene DiSavino of Rivervale, NJ, “He will not survive it … it would be regressing back to the institutions, back to not caring, just doing, just warehousing them … not recognizing what's important, and just abandoning them.”

“A Place in the World: Living with Adult Autism” airs on “Nightline” this Friday, October 7, 2005 at 11:35 p.m. (ET).

Ted Koppel is the anchor and managing editor of “Nightline.” Tom Bettag is the executive producer. “Nightline airs at 11:35 p.m. weeknights on the ABC Television Network.