The Montgomery County Board of Education voted 4 to 3 last night against closing Sligo Junior High School, whose supporters waged a long emotional campaign to save.

But what might have been a great victory for supporters of the embattled school on Dennis Avenue instead left nearly all preplexed as the board failed to resolve the problem of declining enrollment in the Silver Spring area. There could be another move to close the school next year; a move to reconsider last night's vote tonight is even a possiblity.

The board took no action on a proposal to close Eastern Junior High School, which was considered the alternative to closing Sligo. But the staffing problems at Eastern caused by exceptionally low enrollment there remains. Many in the Eastern community -- who also waged an enthusiastic campaign to save their school -- were clearly upset at the board's failure to resolve the problems of the Silver Spring schools.

"It was supposed to come to a head tonight and it didn't," said Eastern Principal Joe Villani. "Somebody will have to do this all over again."

"We got what we wanted. We're open," said Sligo PTA President Marion Leach, "but the board didn't solve any problems."

The celebration Sligo supporters had planned whether they won or lost was quickly dubbed a "limbo party" as they filed out of the board's meeting room in Rockville.

Board President Marian Greenblatt suggested that the board take up the issue of low enrollment in the Silver Spring area tonight, when further school closing decisions are sceduled.

However, it was unclear whether the subject wil be addressed tonight and, if it is, whether there will be a vote on the proposal to close Eastern or to reconsider the vote on Sligo.

The school board's decision on which schools to close conclude a process begun almost a year ago when the board agreed to develop a comprehensive five-year plan to adjust the school system to delcining enrollments.

Over the last two months that process generated many similar activities at the 11 schools being studied for closing. PTA strategy meetings lasted until late at night, there were emotional rallies at the schools and finally overflow crowds of parents and students equipped with buttons, placards and banners packed the board's public hearing.

The message from each of the 11 was the same: Don't close our school.

For the supporters of Sligo Junior High, the campaign to save their school became a kind of crusade, fueled by a community-wide sense of injustice. The people of the Four Corners area and the other communities that send children to the 20-year-old Dennis Avenue school had faced the threat of closing three times in the last four years. Their neighborhoods had already been hit hard with the closing of elementary schools.

So they began to organize in October after they learned Sligo had been marked for closing on a "hit list" drawn up by the school administration.

Their own hope was to demonstrate so much support for keeping Sligo open that the board would choose somebody else's school. Their only tactic, as the cadre of school closing veterans on the PTA freely conceded, was to bring as much political pressure to bear on the board as they could muster. The board, they pointed out, is after all, an ejected body.

With buttons and bumper stickers, bedsheets banners and mimeographed leaflets. Sligo's ardent partisans mounted their drive. As Sligo's carefully orchestrated campaign was hitting its stride, alarms went off in the community around Eastern Junior High School, on University Boulevard four miles from Sligo.

Sligo supporters scored a minor victory when the board voted at the last minute to add Eastern to the list of schools it would consider shutting down.

As it was clear that one junior high would have to be eliminated in the Silver Spring area, where the enrollment decline has been sharper than anywhere else in the county, the communities of Sligo and Eastern found themselves pitted against each other in a contest for survival.

The demise of one school appeared to many the salvation of the other.

Sligo's tide crested first in mid-November when more than 300 parents, teachers and neighborhood residents flooded the school's hearing before. A parade of witnesses roundly denounced the case the school administration had made to close Sligo, stressing the best defense Sligo had -- it's relatively high enrollment of 863.

Widly cheering throng underscored high points of the testimony delivered by Sligo supporters.

It was an impressive demonstration.

But the Eastern community, which complained it had only three weeks to prepare a defense, had yet to make its case, which relied on the key fact that a $3.4 million renovation was completed at the school only three years ago.

Eastern's supporters got their chance before the board Monday night. The crowd was just as large, if not larger than the one at the Sligo hearing, and the arguments in behalf of Eastern were just as vehemently accented with applause.

Last night, board members Daryl Shaw, Carol Wallace, Joseph Barse and Blair Ewing voted to keep Sligo open. Board President Greenblatt and members Eleanor Zappone and Elizabeth Spencer voted to close it.

The board also voted last night to close Randolph Junior High School on Hunters Lane in Rockville. Its students will be transferred to Belt Junior High in Wheaton next fall.

As a result of another vote, a vocational-technical center will be added to Wheaton High when that school is renovated. The center could open as early as the fall of 1983.

The board decided to add the ninth grade to Walt Whitman High in Bethesda and John F. Kennedy High in Silver Spring next year.