Baltimore County's school board is scheduled to vote tonight on whether to renew Superintendent Joe A. Hairston's contract for a third four-year term. Mr. Hairston has, by and large, done a good job, and he has undoubtedly survived this long by keeping a low profile and not making waves. But in a county with an increasingly diverse student population and some predominantly minority schools that are significantly lagging in achievement, Mr. Hairston needs to be more vocal and aggressive in tackling problems that reflect uneven progress.

Although the county has one of the state's best-performing school districts, it still suffers from some extremes. A national foundation ranked the district tops among large urban districts for graduating African-American males. Yet an analysis by The Sun last year showed that several high schools - including those with predominantly African-American student populations - had unacceptably low passing rates on the High School Assessment tests that are required for graduation starting in 2009.

Mr. Hairston has tried to address issues of disparity and academic underachievement by raising standards - eliminating low-level courses and increasing Advanced Placement courses - as well as expectations that every student could meet them. He installed a college prep program that helps middling high school students reach their potential through tutoring and specialized training. He also used technology to help ensure more equitable distribution of resources among schools and better tracking of individual student progress.

But an effort last year to outsource a major revamping of the curriculum was ill-conceived and engendered some bad feelings among teachers. And his commitment to school-based leadership - giving principals more autonomy in exchange for accountability - doesn't mean he shouldn't exercise strong oversight.

Mr. Hairston has acknowledged that challenges remain for the district. Most important, he needs to move more aggressively to help principals and communities turn around the handful of schools, including Woodlawn High School, that are in various stages of restructuring because of poor performance as well as those schools with large numbers of students who are not passing state-required tests. That will mean working more forcefully to ensure that those schools have not only strong principals but also quality teachers. Mr. Hairston owes it to his students to give each of them every chance to succeed.