"Everything You Always Wanted to Know But Were Afraid to Ask: See your school nurse with confidentiality." So reads a sign on the door of Gar-Field High School's health clinic.

Usually, when public health nurse Ernestine White arrives at 7:30 a.m., she finds two or three students waiting.

Most of the time, they're fine physically, she says. What they do need is someone to talk to -- about their parents, about drugs, about sex, or school work, or peers.

"I try to get them settled down so their problems don't become problems in class," White said. And when those students have shouldered their book bags and gone down the hall, more come to take their places in the auditorium's windowless projection room, the only place Principal Roger Dallek could find in the crowded school for White to hang her shingle. So many teen-agers come to see her during her 4 1/2 hours there that some days she's late leaving for her next school.

"I just can't leave with a student saying, 'I really need to talk to you.' " White said. "I'd worry about them."

In a program begun this year by the county health department, Prince William County's six high schools, and the two in Manassas and Manassas Park, are for the first time staffed most of each day with registered nurses.

Also, each nurse is responsible for working two afternoons a week at the middle schools that feed the high schools. Health problems in the elementary schools are handled by school secretaries and parent volunteers.

The Task Force on the Health Needs of School-Age Children, headed by Virginia Secretary of Human Resources Eva S. Tieg, recommended in its report last year that schools have at least one nurse per 1,000 students. The Prince William Public Health District, which includes the county plus the two cities, is far from meeting that standard.

But health district director Jared Florence said he plans to hire another nurse next year, and hopes to expand the program to include better coverage for middle schools and eventually elementary schools.

The focus of the Prince William school health program is not so much on skinned knees and sore throats as on what Tieg's report calls "the new morbidity" -- alcohol and drug abuse, violent behavior, dropping out of school, suicide, depression, and teen-age pregnancy.

"I have trouble separating these," Florence said. "They're all adolescent crises."

Said White: "A lot of kids come in here with home problems. A lot of them turn to sex -- or to drugs -- because they're looking for a way out."

The school nurse program came about because of a concern among local officials over teen-age pregnancy. In 1985, Prince William County had the highest rate among the Northern Virginia counties, and Manassas' rate was second only to Alexandria's.

Under a 1986 pilot project, the health department supplied one nurse to work in Manassas Park High School, Osbourn High School in Manassas, and county high schools Stonewall Jackson and Osbourn Park. According to Florence, the pregnancy rate for Manassas dropped by 58 percent.

Yet the teen-age pregnancy rate in the county has been climbing, according to health department statistics, as has the rate of sexually transmitted disease among young people. The success of the Manassas pilot project persuaded the Board of County Supervisors to expand the program into more county high schools, Florence said.

"You have a lot of students who are sexually active here," White said. Her role as the school nurse is to "try to talk to them about morals, urge them to talk to their parents. But there comes a point when you say, 'If you're going to be sexually active, then you must be protected.' "

Teen-agers are referred to the health department's family planning clinics at department headquarters in Manassas and at satellite offices in Woodbridge and Dumfries.

There, teen-agers have a complete physical, with tests for venereal disease, and are given prescriptions for contraceptives. Everything is free and, under Virginia law, completely confidential.

"We are emphasizing safe sex," White said. "The health department is also giving condoms and foam to the girls for their sexual partners to use."

Recently a group of residents told the county School Board that condoms and foam had allegedly been distributed to a girl by a public health nurse on school property, which is contrary to school policy.

According to Florence, the incident has been investigated and "appropriate action" taken against the nurse involved.

The allegation of the incident is the most recent evidence of a simmering controversy that has dogged the nurses ever since the public health department placed them in the high schools.

The current arrangement is also opposed by local members of the National Association of School Nurses who have been lobbying the county School Board to take over the program.

"The public health nurses are too allied with a clinic," said Sandy Thompson, a member of the association.

"The public health nurse is more community oriented. The school nurse is more growth and development oriented. It's the difference between taking your child to a pediatrician and taking him to a general practitioner."

Thompson said the association hopes to persuade the state to require school systems to employ their own school nurses rather than bring them in from public health departments or elsewhere. Currently, Alexandria is the only Northern Virginia school system that employs its own nurses.

While sex is a major concern for many teen-agers, it is not the only concern of those White sees. Some are on the verge of running away from home, and White said she is often the only person urging them not to.

Eating disorders are also a problem. One of White's fellow school nurses, Joyce Andrew, said that when she tried to organize an exercise class for overweight seventh graders, extremely thin girls showed up for it, too.

"Twenty-five percent of the kids I talk to in school have eating disorders," she said.

White said she occasionally gets notes from parents who ask her advice just as their children do.

Advising and counseling and listening take most of her energy, she said. "It's a challenge."

"If I didn't pray a lot, and if I didn't have a lot of love inside me, I'm not sure I could keep going," she said.

"I sometimes hug the kids -- just hold them and hug them in a motherly way. They need that."