When Fairfax County's new sex education program was unveiled a month ago, it appeared destined to gain the broad-based support of the community. Even some conservative groups -- which traditionally have opposed efforts to expand the Fairfax program -- gave the proposal their cautious endorsement.

But after four weeks of scrutiny, a number of citizens say they are not satisfied with the information released thus far about the program. And several say they plan to ask the school board, which is scheduled to act on the proposal May 14, to delay a decision until fall. The citizens will have a chance to voice their opinions tonight, at a public hearing slated to begin at 5 p.m. in the Luther Jackson Intermediate School auditorium, 3020 Gallows Rd. As of early this week, 89 people had requested time to speak at the hearing.

"I think this program, as it is proposed, leaves a lot of unanawered questions," said Robert Smith, former school board member from the Annandale District who describes himself as a conservative on the sex education issue. "I think the board ought to refer the proposal back to planning and ask for a new program in the fall."

Perhaps the greatest fear being expressed by some parents concerns topics that will be allowed in classroom discussion. While the program materials appear to be tasteful and carefully selected, the parents say they want to make sure there are limits to what kind of topics can be discussed. The new program would allow discussion of any subject that came up in class. In addition, in keeping with school board policy, guest speakers could be invited at the discretion of the principal.

"I asked school staff members if homosexuals would be allowed to speak to classes, and I was told that guest speakers would be invited at the discretion of the principals in the individual schools," says Joan Harris, a McLean parent.

School staff members say the teachers will undergo intensive training in sex education to enable them to answer most questions. School officials add that guest speakers in sex education classes will be admitted under the same procedures as guest lecturers in other courses -- with the permission of the principal.

"I doubt if principals will allow them (homosexuals and abortion clinic personnel) in the classroom," said Mary Sykes, an Area IV curriculum specialist.

Some parents also are insisting that children should only be able to take the course with parental permission. As currently proposed, parents must notify the school that their child cannot take the course. Although that is a subtle change, some parents contend it is an important one.

Smith, who was a school board member when the board first began considering revisions in the sex education program, said he spefically asked what the board keep the rule requiring parental permission to take the course, instead of the rule currently proposed. "That was one thing which I specifically asked for at the time," Smith recalls, "and the board was in agreement on it. Unfortunately, no vote was taken. It was just summarily included in our directions to the school staff."