THE SUPERINTENDENTS of large urban school districts last in their jobs about 21/2 years on average, a turnover rate that compares unfavorably with football running backs and other jobs whose stock in trade is the ability to take a hit. So it is no particular shock that Eric J. Smith, the nationally recognized superintendent of Anne Arundel County schools, has announced that he will resign this fall after barely three years on the job; his tenure actually bested the national norm. Still, Mr. Smith's departure is a setback for Anne Arundel schools, which made impressive strides during his three years at their helm. And his experience, marked both by academic success and political struggle, is an object lesson in the embattled state of one of America's toughest public-sector jobs.

Having come from Charlotte, where he was lionized as an educational wunderkind for having narrowed the racial achievement gap between black and white students, Mr. Smith arrived in Anne Arundel with a splash. His compensation package of $300,000 a year stunned the county, and his reformist agenda for the 75,000-student system put people on notice that business as usual was finished. He was clear on his priorities: to raise standards across the board while also righting decades of wrongs by insisting that the least advantaged kids be pushed, coaxed and cajoled into the same demanding, quality courses available to more affluent students.

After three years, his program achieved plenty. Black high school students' scores rose on standardized tests; participation in Advanced Placement courses more than doubled; and every county elementary school met state testing targets. But his personal style -- by turns charming, incisive and arrogant -- hurt in a highly political job dealing with multiple constituencies. Parents liked him, but teachers and school board members resented his highhandedness. Nor did it help that just one of the eight school board members who hired him remains on the board today -- not an unusual turnover for large urban school districts, but treacherous for superintendents. Like many superintendents, Mr. Smith finally decided that the headaches outweighed the rewards. And like many superintendents, he had plenty of job options: He took a job at Harvard University.