Every weekday as Marty Wasserman commutes between his home in Maryland and his job in Virginia, he spends the hour each way listening to the latest in cassette tapes.

While Beethoven and Anne Murray are among his favorites, Wasserman is more likely to listen to a droning voice describe "Thyroid Dysfunctions in Newborns" or "Hemoglobinopathies" from his pediatric tape collection.

But Dr. Martin P. Wasserman, a pediatrician, doesn't spend his workdays in a medical office. And while he also has a law degree, it's not a legal career he pursues.

Wasserman heads Arlington County's Department of Human Services, the agency reponsible for myriad health, mental health and social programs, and he says it's exactly the type of post he envisioned when he decided to wed the medical and legal worlds.

"Here you can put together a program for the handicapped or a new family violence program, and you know on faith you're making a contribution," said Wasserman.

Wasserman, a 42-year-old high-visibility official with salt-and-pepper-colored hair, took the $67,000 job seven years ago and today his agency -- with a budget of $18.8 million and a staff of about 400 -- is the only one of its kind in Virginia, where most localities spread the same functions among separate departments.

"It's not the most sedate county agency, for sure," said county board member Albert C. Eisenberg. "It's an agency that deals with the full range of human problems and needs . . . They see the effects of their programs up close in a personal way every day."

That's the kind of intimacy Wasserman thrives on and that led him and his top staff to huddle outside an unapproved shelter for homeless men one cold morning last year as county police prepared to close it down.

"He knew it was going to be a sensitive issue, that the police were going to have to raid, and we were going to have to be providing services," said Karen A. Percy, Wasserman's assistant.

Within four hours after police moved in, Wasserman and aides had fed the 14 men who had been housed at the illegal shelter and delivered them throughout the county, some to approved shelters, some to detoxification centers and others to jobs.

"He gets involved in situations that are going to have a significant impact on the community," said Percy.

As a result, Wasserman has had his share of criticism and acclaim in an unpredictable job that has entailed feuding with school nurses over job assignments, reassuring people fearful that they might contract AIDS (Acquired Immune Deficiency Syndrome), meeting with members of Arlington's large refugee community and lecturing wherever he can to push his strong antismoking views.

"Our experience has been that he is very open to communication and very sensitive to the needs of the community in general," said Orlando Mayorga, executive director of the Spanish-Speaking Committee of Virginia, which represents Hispanics, the fastest-growing minority in Arlington.

Wasserman gets lower marks, however, from Kim Cook, a representative of a Vietnamese self-help group. She was angry with him when her group lost a federal grant and said she wants Wasserman's agency to be more aggressive in planning local programs to replace federal refugee programs that are likely to be eliminated. Wasserman said there are only so many dollars for refugee programs and said his agency is planning ways to spend county money better.

Wasserman came to his job by way of a tour in the Public Health Service on the Hopi and Navajo Indian reservations. He and his wife, Barbara, an internist, practiced there briefly during and after attending Johns Hopkins University Medical School in Baltimore.

"We worked with them to try to get Western medicine introduced to the Indians," said Wasserman. That effort once led him to work with his medicine alongside a tribal medicine man for whom "sand-painting" was a medical panacea.

Wasserman's experiences with the Indians made him a disciple of preventive medicine. He said he believes he can do more to improve people's health by focusing on prevention on a community-wide scale than by just treating the sick.

The treatment that the sick, particularly child abuse victims, received from the judicial system led him to enter the University of Maryland Law School in Baltimore, just down the street from his job as director of the university hospital's pediatric outpatient clinic and emergency room.

During his postgraduate medical training at the University of Rochester, Wasserman said he encountered child abuse cases including one that brought him to court as a witness for the prosecution. The state won the case, but Wasserman said he became furious when the child was returned to his parents. He was also miffed with his treatment on the stand by defense lawyers.

"Surely the legal profession and the medical profession didn't understand each other . . . I decided that some day I wanted to be in a position where I could help the cross-communication of the two professions."

Although he has never practiced law, Wasserman said it gives him extra insight on problems that arise in his job, such as when his environmental health unit has to close a restaurant.

"You can use the law to change things," he said, sitting in his cramped knotty-pine office near Arlington Hospital. It is cluttered with dusty cartons of files "on things that might come up sometime," an IBM personal computer, "poor takeoffs" on Picasso art, dozens of tapes on the latest developments in pediatric medicine, and 22 pictures of his wife and their two children, Brad and Torrey.

Although Wasserman, a former Connecticut all-state tuba player, belongs to a dozen professional organizations that keep him working late many nights, he said he has dropped some activities to spend more time with the family.

Some of that time is spent riding their two horses at his home in Howard County, swimming in the family pool, baking "Coca-Cola cakes," and refereeing for his children's sports teams.

"He's an over-achiever," said tennis and racquetball partner Anton S. Gardner, a deputy county manager who remembers the days when Wasserman wore clogs and buckskin jackets to work. "He's clearly a maverick, an extrovert . . . He's not your typical main-line bureaucrat."

Wasserman said he is striving to become a better administrator and trying to avoid so much personal involvement in the issues that come across his desk.

"He tells me that you can't solve everyone's problems," said his secretary, Michael A. Bradley, but "He keeps his doctor's coat behind the door . . . . If a child comes in with a current case, he stops what he's doing, puts on his coat, and away he goes" to check on that child.