HAVING SUFFERED the resignation of its ethically myopic superintendent in May, the Prince George's County school system has entered into another period of leadership limbo. The current acting chief, veteran administrator Howard A. Burnett, is a stopgap serving a 12-week term; he plans to retire as soon as possible after that -- perhaps as early as the fall. That's not much time, to put it mildly, to find the right candidate to lead one of the nation's 20 largest school systems -- a sprawling district encompassing 200 schools, 136,000 students and 8,000 teachers. Making matters worse, almost anyone with the desire and qualifications to lead so large and complex an operation is likely to have found a position for the fall elsewhere. And since the county's appointed school board is to be dissolved next year in favor of an elected one, it's unlikely to locate many good applicants willing to sign up for a long stint -- in this case even four years would be a long stint -- clouded by the insecurity of knowing the bosses will change barely a year later.

Whatever choice the board makes, it would be wise to take a more careful, considered approach than it did two years ago in selecting Andre J. Hornsby, the recently departed schools chief. Mr. Hornsby, whose record in previous jobs was marred by bitter controversies, became entangled in ethical problems almost as soon as he arrived in Prince George's. A more fastidious examination of his record by the school board might have saved the county the upheaval it is now undergoing.

Despite signs of modest progress -- namely, somewhat higher test scores -- the county schools remained plagued with problems; they are among the worst in Maryland. A new schools chief will face a pronounced racial achievement gap, poor attendance, "permanent freshmen" who repeat ninth grade endlessly, underperforming schools and dozens of facilities badly in need of major repairs, among other challenges. In reckoning with such a daunting agenda, the county simply cannot afford another exercise in poor judgment by the school board. A steady, competent, ethically exemplary leader is needed, and board members should apply themselves to find one.