For Joyce Tobias of Annandale it was discovering her 16-year-old son stuffing a bong under his mattress.

For Joyce Nalepka of Silver Spring it was a Capital Centre rock concert at which her son became sick from the fog of marijuana smoke.

For Judy Reidinger of Falls Church it was a drug-related suicide in her family.

These area mothers are part of a nationwide surge of parents who have banded together to fight the alarming epidemic of adolescent drug abuse. Through parent-education and action groups they are teaching members about teen-age drug abuse and developing strategies to deal with the problem. In many cases this means practicing "tough love" (see story below) -- by establishing curfews, enforcing house rules, chaperoning parties and forbidding drugs in the house.

This "parent movement" -- which experts say includes about 700 groups nationwide and nearly 60 in the metropolitan Washington area -- is partially responsible for "the beginnings of a turnaround in the drug use by teen-agers," says Dr. William Pollin, director of the National Institute on Drug Abuse.

"As of a few years ago there was a general feeling among parents of nihilism and hopelessness in dealing with the drug problem. They were inadvertently communicating these feelings to their children. But now there is a very real commitment on the part of rapidly increasing numbers of parents to get together with other parents and decide they're not going to stand for it anymore."

Instead of getting stuck in debatable issues -- such as how harmful illegal drugs like marijuana are compared to legal drugs like alcohol -- parents are concentrating on the "unquestionable notion," says Pollin, "that drug use on a regular basis by kids is not a good idea, and going to school stoned is a dreadful idea."

These tactics appear to be working, he says, pointing to a NIDA-University of Michigan study of student drug abuse in 1980, released last week. The study, he says, contains "some good news and some bad news.

"The bad news is that in the past 20 years there has been a 10- to 20-fold increase in the use of all drugs among young people, making the level of drug use as high or higher than in any other industrialized country.

"The good news is that for the second year in a row, there's been a decrease in the daily use of drugs by high-school seniors. Of the 16 different categories of drugs -- including cigarettes and alcohol -- the use of all but two have leveled off, or is down."

Drug use, however, among high-school seniors remains widespread, according to the study, with nearly two-thirds having used an illicit drug and nearly two out of five having used an illicit drug other than marijuana. But it also reports a sharp drop in regular cigarette smoking, a drop in marijuana use and a drop in PCP use.

"Parental involvement," says former White House drug-policy adviser Lee Dogoloff, "is the way to make change. Experts and laws are important, but in a battle of attitudes there's a lot you can do at home. The fact that parents are getting this idea simultaneously in community after community around the country shows how profoundly important it can be."

These hundreds of parent groups were recently brought together under the newly-formed National Federation of Parents for Drug-Free Youth (NFPDFY), headquartered in Silver Spring. "It's the most exciting thing," says Dogoloff, who is executive consultant to the group, "that I've seen in the area of drug prevention."

Washington-area parent groups also are forming a network, through a public service program sponsored by Drugfair. Kensington mother Rita Rumbaugh, an active member of a parent group in her community, is scheduled to announce the formation of the Metropolitan Washington Parent Network at a press conference today.

The network will run a free parent leadership-training seminar next month, and Drugfair plans to run about 30 community workshops on teen-age drug abuse throughout the spring.

Most parent groups are based on three "gets," says Bob Kramer, Anne Arundel County substance abuse prevention coordinator and NFPDFY board member.

Get informed.

Get involved.

Get together with other parents.

"If a parent says, 'Johnny, I better not catch you shooting marijuana' they'll lose their credibility because the kids realize they don't know what they're talking about. If a parent doesn't know drug jargon, their kids may be making drug deals over the phone without their knowing it.

"Getting involved with your kids doesn't mean doing a midnight search-and-seizure raid. It means sitting down and discussing your values and taking a clear, consistent and informed stand on drug abuse. And when you make rules, stand by them.

"Drugs have really changed the whole ballgame of adolescence. Parents need to equip their kids to be able to say 'no' to their peer group effectively. Getting together with other parents before there's a problem can help both the kids and the parents. Kids need an ally, and that's the parent. Parents need and ally, and that's another parent."

Kramer's advice: "Write down the names of your child's five closest friends and 15 closest acquaintances. That's the child's peer group. Call up those parents, get together and talk. Don't accuse each other, but concentrate on the positive steps and guidelines you can agree on to help your kids stay off, or get off, drug abuse."

Counselors, parents and professionals in substance abuse added these suggestions for concerned parents:

Be prepared for questions about your own drug (including alcohol) habits. "You may have to clean up your act, too," says one father. But don't feel you have to stop using all intoxicating substances, adds drug education specialist Thomas Gleaton. "I contend that's an adult privilege, when used responsibly," he says. "But it's a decision adolescents aren't equipped to make emotionally, socially or economically."

"Don't push alcohol on your kids in hopes they won't then use drugs," says Patricia O'Gorman of the National Institute on Alcohol Abuse. "It doesn't work."

"Praise your child and give out big warm hugs when they're good," says one father whose child was nearly killed from alcohol abuse.

"Don't blame yourself," says Iola Scrafford, founder of the Crossroads Drug Abuse Contrl Program in Fairfax, Va. "Don't worry about what would have happened if you'd done something differently -- it may not have made any difference. Concentrate on what to do about the problem now. If your child won't go for help, get help for yourself."

Don't panic. Look at the whole picture -- is the child in trouble in school, is there a behavior change, are there other problems?

"Think back to your own adolescence," says Scrafford, "and remember that some kids today use drugs as a phase in their life -- not that I'm condoning it -- and it goes away.

"Don't come down too hard until you know."