Sarah Roisman comes from a good home. Her mother, Lee, is a dentist. Her father, Richard, is a lawyer. The youngest of the family's three children, Sarah always did well in school, had well-mannered friends, and spent her summers playing softball at a camp in Maine.

She sneaked her first glass of vodka at 12. By the time she celebrated her bat mitzvah, she had been drinking heavily on weekends for months. At 15, she was supporting a $100-a-day cocaine habit, popping prescription pills from her friends' parents' medicine cabinets, and consuming more than a bottle of champagne in a night.

Her addiction grew in the brocaded living rooms of Lower Merion, not the razor-wired alleys of North Philadelphia. "It doesn't matter very much where you're located," Sarah said. "It's easy to find dealers. Cocaine is a classy drug, so young rich kids are dealing it on the Main Line."

What isn't so easy, she discovered, is getting and staying sober. The mantra in recovery is "One day at a time." Some days are harder than others. And one of the most challenging is Dec. 31. So this year, for the third time, Sarah and her family are throwing a sober New Year's Eve party open to all.

"New Year's Eve is a rough night for people in recovery," said Casey Duffy, founder of Sober Samaritan, a nonprofit in Malvern that funds scholarships for alcohol and drug treatment. "It's the one night where you kind of have to run and hide. Everything's centered around drinking."

Duffy met Sarah three years ago at the annual sober Christmas party he gives for fellow alumni from the Caron Treatment Center in Wernersville, Pa.

"She stood up in a room full of 40 people, most of them adults, and said, 'I have this dream, I hope you will help. But even if you can't help, I hope you'll support it. But even if you don't, we're doing it.' "

The dream, she explained, was to organize a substance-free New Year's Eve party, solicit donations for the food, decorations, entertainment, and soft drinks, and use the admission fees to pay for a teenager like her to go to rehab at Caron.

She wrote down a condensed version of her descent into addiction and the path back she had found, printed it on Sober Samaritan letterhead, and began making the rounds of law offices, restaurants, and businesses in Center City and the suburbs, asking for donations in cash or in kind.

She was willing to be frank, she said, hoping it would show people that addiction can affect anyone.

"They can see you can live on the Main Line and have a great life and have everything you ever dreamed of and still have this disease," she said.

On Sept. 11, 2006, Sarah passed out in class at Harriton High School. The school nurse called her mother.

Lee Durst-Roisman remembered looking at Sarah on the way to the doctor's office and thinking, "She must be either hungover or high. I had never seen her like that."

In the waiting area, Lee Durst-Roisman said, "I looked at all these other girls in their private-school uniforms sitting straight, and there, my girl is sprawled out across three chairs. I'm mortified."

When they were led into an examining room, Lee Durst-Roisman watched as Sarah climbed onto the table and stretched out. "I scribbled on a scrap of paper and handed it to a nurse."

The note read: "I think she's doing drugs. Please tell the doctor."

After she agreed to a drug test, Sarah decided to prepare her mother for what she was about to learn.

"I'm sorry, I'm a mess," she said, breaking down.

She had been high the night before, but could only guess what was in her body. The results came back positive for cocaine, alcohol, marijuana, Xanax, Oxycontin, and amphetamines.

Three days later, Sarah entered Caron.

"It was hard," she said. "It was like drugs and alcohol were my best friends. I did them all the time, and that's how I lived, and all of a sudden, they were gone."

She spent her 16th birthday, Christmas Day, in rehab and stayed for three more months.

It cost her parents close to $60,000.

To afford the treatment, they sold their house, quit their golf and tennis club, and left their synagogue. They also moved to Chester Springs to give Sarah a fresh start in a new community.

"We had to reprioritize where we were spending our money. And we still do. If someone says your kid has cancer, you're not going to do this?" Lee Durst-Roisman said.

Their health insurance covered only a small portion of the expense. "Why they don't consider it a disease is a whole other issue," she said.

Lee Durst-Roisman belongs to a support group now. "Every parent in our group had no idea when their kid was doing drugs. Even heroin. They're very crafty kids. And they're so smart. They're master manipulators; it's part of the disease. Until they have their DUI or lose their job or end up passed out in an ER . . .. You just pray that when they hit bottom they haven't died or hurt themselves or anyone else. That's the scary part of what we learn as parents. The only thing that helps them is letting them find their way."

Sarah said she realized how fortunate she was to end up in a treatment center like Caron.

"People with less privilege aren't so lucky, and I don't want anyone to be denied because of money."

According to the U.S. Substance Abuse and Mental Health Services Administration, last year, 1.8 million young people ages 12 to 17 needed treatment for alcohol and drug abuse, but only 150,000 received it at a licensed rehabilitation facility.

In its first year in 2008, the party - dubbed the Denim and Diamonds Ball - drew 150 people and raised more than $13,000. With Duffy's help, that was enough to cover the entire cost of one girl's treatment.

Last year, because Sarah was at Prescott College in Arizona and had less time for fund-raising, the party brought in only half as much. This year, Sarah, a senior, has ceded most of the work to her mother.

"We're proud of her," Lee Durst-Roisman said. "She decided she wanted to give back to the place she got treatment because she really felt they saved her life. She does a lot of good for a lot of people."

For the recovering community, Lee Durst-Roisman said, the New Year's Eve bash is a relief and a pleasure. "Even if we don't raise enough money, it's a good time."

One of the regulars, Bill, who asked that his last name not be used, said, "It really is fabulous. This is a great opportunity to party, dance, make noise, and not have to worry about being around a lot of alcohol."

He attends with his wife, his 28-year-old son, and his 23-year-old daughter. The entire family, he said, is in recovery. And their sobriety began six years ago when their daughter, then a junior at Conestoga High School, entered Caron.

"They provided a scholarship," he said. "Recovery is difficult enough without using every last penny you've got."

During a recent fund-raising trip to Whole Foods, Lee Durst-Roisman said, she made her pitch to a manager and showed Sarah's letter.

"She reads it and gets to the bottom and says, 'That's your daughter? I've got one of those!' " The woman's son is an addict and can't afford treatment.

"It's everywhere," Lee Durst-Roisman said. "It's just amazing."

Sarah plans to get a Ph.D. in psychology and specialize in treating adolescent girls.

"There's some idea about addiction that prevents people from getting help. But I wouldn't change anything about my life. I think I know myself better than a lot of people my age do, and I have support from the most incredible people."

Her family, she said, has been changed for the better, too.

"We've been through the wringer and back, and we survived."

If You Go

The Denim and Diamonds Sober New Year's Eve Ball runs from 8 p.m. to 1 a.m. at the Fairmount Athletic Club, 499 S. Henderson Rd., King of Prussia.

Tickets are $30 in advance, $40 at the door.

For more information, contact Lee Roisman at leeroisman@gmail.com or sobersamaritan.com.EndText

Contact staff writer Melissa Dribben at 215-854-2590 or mdribben@phillynews.com.