The Masons of Largo could be candidates for the quintessential American family. Philip A. Mason is a government worker, his wife Rowena is a housewife and they have three healthy children.As a family, they are young, vibrant, intelligent, productive, close, carring -- and in trouble.

Cindy Mason, dark-haired, almond-eyed and, at 14, taller than her mother, has tried drugs and ran away regularly because "I had Mom and Dad all over town to look for me and it kind of felt good that they cared."

Phil Mason Jr., 16, brags that he did whatever he wanted whenever he wished. Though told by his parents to stay home "on restriction," he went out one night with friends who invited him to "go to the movies, find a couple of girls, whatever, maybe go down to D.C." He didn't come back until one the next morning. That was not unusual.

Rowena was distraught. She was confused and appalled by her lack of control over the two oldest children and frightened that her youngest, David, 11, would soon follow his siblings into the dangerous world of out-of-control teen-agers. The deteriorating situation at home threatened to disrupt Phil Sr.'s work: "I couldn't push it out of my thoughts when I was at the office."

He sought help through an employe assistance program where he worked, the federal Department of Agriculture, and was referred to the Family Service Center at the University of Maryland's College of Human Ecology.

This center, which opened last September, offers counseling for families and couples in much the same way a dental school offers reduced-price orthodontics.

It serves as a laboratory for students who are studying to become marriage and family counselors. In exchange for serving as "guinea pigs" and relinquishing the traditional confidentiality between therapist and client, families receive counseling at greatly reduced prices. Sessions of about an hour cost from $5 to $45 depending on income, number of family members and other financial obligations. Family counselors in private practice usually charge $50 to $60 an hour.

The four-semester program, which accepts 10 students each year, leads to a master's degree in science in family and community development. During their second semester, students are assigned cases and counsel their patients, usually once a week, under the guidance of professors who are trained counselors.

Families seeking aid agree to be observed by students in a booth behind a one-way mirror. Often sessions are videotaped for use in classes.

Supervisors in the booths frequently phone into the counseling room during the sessions to offer guidance to student therapists, and sometimes go into the room to help with the therapy.

Presently, nine student interns are seeing about 20 client families, and according to center administrator Joan D. Liversidge, there is room for more clients.

Liversidge says news of the center's opening has been received with enthusiasm by other community agencies. Federal budget cuts are slicing into already overloaded counseling services provided by public institutions while inflation-burdened families have less money to spend on mental health.

Increasing unemployment and inflation is likewise hurting family harmony. Economic stress is a major source of conflict for families. Though she could cite no statistics, assistant professor Eleanor D. Macklin said an increasing number of the center's clients are beset with financial difficulties.

"People are living beyond their means and suddenly find they are way overextended and have to adapt their lifestyle. It's hard for the man not to feel he's somehow failed, let his wife down," said Macklin, who supervises graduate interns. Financial problems are "an added stress for many couples, often increasing problems that are already there."

Explaining the philosophy behind family therapy, Macklin said, "Most problems in human living really grow out of our intimate relationships, so why not deal with the whole unit within which the problems originated?" She believes trying to help a troubled person without involving the whole family is like "working with my arms tied behind me." She said most problems "either impact on the other people in the family or have been essentially caused by interaction with the other people."

"A therapist can help an individual," Macklin said, "but therapy progresses so much more quickly if you can get everybody into the act at one time."

Direct observation of therapy in progress is new and is "a tremendous aid" in improving both therapy and the training of therapists, she said.

In traditional training, she said, the trainee talks about a therapy session with a supervisor, using notes made after the session. But guidance is hampered because "the supervisor has to go by what the therapist is reporting," Macklin said. Video tapes and direct observation of the therapy in progress "cuts through an awful lot that's guesswork otherwise."

Families in therapy do not seem to mind being observed or videotaped, Macklin said. "In my experience, they soon absolutely black it out," she said. At first, before they get used to it, someone in the family, often children, will ask if there is someone in the observation booth and wave, "but soon they get drawn into what they are doing because what they are talkling about is so gripping."

Student therapist Marilyn L. Cohen, who works with the Masons, said at first she found direct observation supervision "jarring" but "it gets easier. In one sense it's reassuring. You don't have to do all the thinking yourself."

Lois B. Valladares, another student therapist, who counsels two families, said the program has prepared her well for her career in family therapy. "It's dynamite. . . . It's really given me a lot of tools and a lot of styles of therapy so I can find my own."

Macklin defends the quality of help available at the family service center.

"In my mind it's like why you go to a medical school, because they are on the forefront of the science," said Macklin. "Though you may be seeing a student, that student is working under the supervision of someone who is top-notch in his field. There is a tremendous advantage to coming to someone in a training institution."

Students are committed to their clients, Macklin said, and are "eager to do a hot-shot job," which helps to make up for years of experience they may lack. What's more, center assistant director Sherri Starr points out, clients are getting two therapists for the price of one.

In addition to therapy, the center also will offer family mediation services, financial planning and family life education courses as it becomes fully operational.

A month of family therapy has already turned things around for the Masons, they said.

Both parents said they have a better understanding of why they lost control of their children. They have learned how to listen to their children, and they have laid down the law. Cindy and Phil Jr. seem to have accepted it.

"We feel like we're back in charge of the situation," said Phil Sr. "It's been beneficial to the children to recognize there's some strength in the family, that there are some rules which are unalterable."

"We were doing even more harm by trying to be empathetic," said Rowena. "We were trying to be fair and figure it out and give the kids the benefit of the doubt instead of being benevolent dictators. I almost felt they were running me instead of me running them."

"Running away was an effort on the kids' part to intimidate us and it worked," admitted Phil Sr.

There are new rules now in the Mason household, and Phil Jr. and Cindy seem anxious to obey.

Phil Jr. confessed that he was surprised when his parents told him that if he ever went off on his own again, "I would be sent down to juvenile authorities in Upper Marlboro as an uncontrollable teen-ager. I tested that. I challenged them, 'You can't do that.' I was telling them it was child abuse. They just informed me that they're the boss and I no longer decide what I am going to do. I have to accept it. It's not that bad."

Cindy concurs. "Now if I run away and I call to be picked up they say, 'You know where home is.' And I say 'But Mom, it's dark outside, dark and cold.' and they say, 'You got there, didn't you?' and when I go home, I'm glad to be at home." She pauses. "It was kind of stupid before. I was kind of ruling my parents. But now it's better."

Therapist Marilyn Cohen said her approach with the Mason family is to "build on family strengths. They clearly have made lots of changes. They were motivated to begin with. This is a family with a lot of strengths."

For information about counseling call the family service center at 454-6180.