Every spring for the past seven years, Sue Rafferty's mailbox has held the bad news -- a letter informing her that she might not have a job as an Arlington County teacher the next fall.

This April was no different, as Rafferty, a social studies teacher, and 167 colleagues in Arlington got RIF (reduction in force) notices, telling them that because of declining enrollment they were being laid off.

By early this week, all but 47 had been rehired on a full-time or part-time basis.

Although Rafferty was among those rehired, the news was not entirely good. With less than a week before school starts, and for the first time in her seven years in Arlington, Rafferty has the guarantee of part-time work only.

Rafferty, who taught at both Washington-Lee and Wakefield high schools last year, will be teaching one class at Swanson Intermediate and another at Thomas Jefferson Intermediate. And since she will be working only one-third of the regular schedule, she will get only one-third, or $8,000, of her former salary.

But Rafferty, who has 12 years of teaching experience, is still hopeful a full-time job will open up; she's heard rumors that a social studies teacher at one Arlington school plans to go on leave and with her experience, Rafferty figures, she may get that job.

But Rafferty is being cautious, too. "I've suffered so many disappointments in the past that I'm not letting myself think about it until I get confirmation."

For Rafferty, the trauma of the annual RIF rites has been even more agitating this year. In June, she was elected president of the Arlington Education Association, the organization representing most of the 969 teachers in Arlington.

"It really has bothered me a lot," she says, "because I feel I've got a responsibility for the membership and I felt I would be letting the membership down (if I didn't have a job)."

Rafferty's colleagues in Fairfax County and Alexandria face no such crisis this year. Fairfax County did not lay off any of its 7,300 teachers, according to school officials. In Alexandria, which has 770 teachers, administrators said 15 teachers were hired last year with the understanding that their jobs were one-year appointments only. Even so, four of the 15 have been offered jobs this fall.

One reason Rafferty has become so accustomed to the annual RIF notices is her teaching field -- social studies. Although teachers are RIFed according to seniority, educators say there is nearly always a glut of elementary, English and social studies teachers -- almost ensuring that teachers in those fields will be among the first to be trimmed.

Being a social studies teacher, Rafferty says, "has made me very frugal. I drive the same car I have had for the last 10 years and, God willing, it will hold up another year or two."

But the strain of facing every summer without the guarantee of a job has forced Rafferty and countless other teachers to question whether they want to stay in teaching. Until she bought a condominium two years ago, Rafferty says, she "lived from year to year."

But her new financial obligations, coupled with continual RIFs, has prompted Rafferty to wonder if she will stay in teaching. "I'm very strongly considering leaving education at the end of the year," she says.

That same sense of insecurity drove Pat Hopkins to resign her Arlington teaching job when she got her RIF notice this spring. Hopkins had been a music teacher and band master for two years at Washington-Lee High School; both years she got RIFed.

"It's the instability," Hopkins says. "The population is continuing to decline and I don't know why it's plaguing the Arlington school system so much, but it is and it's hurting the elective courses especially."

The economic development boom in the county, particularly around the Metro-stop corridors, has led to the construction of large, luxury high-rises. And, according to county planners and other observers, those high-rises are out of financial reach of many young families, forcing them to move farther out for affordable housing.

The changing demographics led the county school board this year to order a study of the possible reorganization and consolidation of secondary schools. The future availability of a sufficient number of elective courses, as well as extracurricular activities, will be incorporated in that study.

Although Arlington offered Hopkins a part-time teaching job, she decided to transfer to a Prince George's County school, where she will be able to teach full time.

"I know there aren't any guarantees in this world," Hopkins says when asked if she expects to escape RIFs in her new job, "but it's a full-time offer."

Hopkins says teachers aren't the only people who suffer because of RIFs. In her teaching field, for instance, Hopkins believes RIFs are particularly detrimental to the students.

Under Hopkins' leadership, the Washington-Lee marching band won two awards, the latest coming last spring at an international music festival in Montreal.

"Being a band director is like being a football coach," Hopkins says. "You have to work from year to year with the kids, bring them along, learn where their weaknesses and strengths are."

RIFs complicate the process, says Hopkins, whose predecessor also was RIFed. "You lose your continuity. You're not sure you're going to be there with them (in the fall)."

And because of the competitive nature of marching bands, she adds, "You have to start planning in July and the kids start practicing in August. You can't wait till September (to learn if you've been rehired). The first football game is then."

Joan Blair is another Arlington teacher who was RIFed in April. Like Hopkins, she had been teaching full time in Arlington for two years and received RIF notices both years. So far, Blair, who is an elementary teacher, has been offered neither a full-time nor part-time teaching position in Arlington.

But Blair isn't about to give up on the teaching profession.

"It's a personal thing," Blair says, "something I enjoy doing. I'd rather (teach) than do almost any job.

"I fully expected the (RIF) letter, and I do sort of expect to go back. But I'm not counting on going back to the same school. Every year, it's sort of bad. You're hanging on, not knowing what your status is."

Still, Blair says, RIFs "aren't really all that grim if you can just sort of hang in there."

And, if she isn't rehired?

"I guess," she says philosophically, "I can always work for the government."