MONTGOMERY COUNTY'S election returns convey a resounding judgment -- and well deserved -- on the county school board. Its present majority has led the school system into an increasingly damaging series of racial, ethnic and neighborhood quarrels. The most vehement and vocal member of that majority, Marian Greenblatt, running for Congress, was decisively beaten in the Republican primary by Elizabeth Spencer.

Mrs. Spencer, who also was a member of the school board, resigned her seat there when she entered the campaign for Congress. That was the decent and proper thing to do. It's not a matter of being priggish about the nonpartisan school board. It's enough to say that the board's work always suffers when it is injected with the attitudes and issues of national politics. Mrs. Greenblatt did not resign her school board seat, and she evidently intends to complete the remaining two years of her term. That would be a mistake. She would do the county schools a service by leaving the board and turning her energies to Republican Party politics, which clearly has a higher claim on her interest.

The school board election was a runoff to select the eight candidates to compete for four seats in November. The two incumbents running for reelection, Joseph R. Barse and Carol F. Wallace, ran fifth and sixth, respectively. They are still on the ballot, but it's pretty clear that the county is looking for a different kind of leadership for its schools.

In the judicial election, Montgomery's voters were right to choose the four judges who are already on the bench. To turn the election into a political attack on the whole selection procedure, as one challenger tried to do this year, is to misuse the process.

In their primary for county offices, the Democrats renominated -- with one exception -- the incumbents for county executive and the council. That exception, William Hanna, in the third council district, was running on a slate that stood for more vigorous checking and balancing of the powerful county executive, Charles Gilchrist. Montgomery County has a three-party system, in which two of the parties run on the Democratic ballot. The primary results mean that, if the various sects of Democrats sweep all of the county government jobs again, the county council will be slightly more adversary to Mr. Gilchrist than in the last four years. But whether Democrats should occupy all seven council seats is an open question, to which we intend to return next month as the campaign gets under way.