MONTGOMERY COUNTY contains some of the wealthiest neighborhoods and best public schools in Maryland. At the same time, the county's students are rapidly growing in number and diversity, thanks to immigration and an influx of Hispanic families. Any Montgomery County school superintendent therefore faces a nearly impossible task: Satisfy the high-tax-paying parents of students in the better schools and simultaneously meet the needs of low-income, non-English-speaking students.

Since taking the job in the 1999-2000 school year, Superintendent Jerry D. Weast has argued that focusing on students' early years is key to meeting this challenge and overcoming the achievement gap. Toward that end, he retooled the curriculum, added individualized testing for children, provided training to help teachers promote and understand the progress of particular students, hired better principals, expanded the number of all-day kindergarten programs, and cut class sizes. These changes have not come cheaply. Since the 2000-01 school year, the county has spent $67 million, mostly on class-size reduction and teacher training, including $18.5 million for the early childhood reforms.

The money appears to have been well spent. Not only did this year's second-graders -- the most ethnically diverse class in Montgomery County's history, according to Mr. Weast -- show overall improvement compared with last year's second-grade class, the gap between white, Hispanic and African American students actually shrank. Notably, scores in the 17 low-income county schools that first received smaller classes and all-day kindergartens increased significantly.

There are a number of lessons to be taken from these changes. All children can learn, but it doesn't happen automatically. Methods have to be thought through, teachers need to be trained and encouraged, and results need to be measured. No less important: Mr. Weast was backed by the county school board, the county government and county parents. This unity of purpose (a sharp contrast to District school governance) allowed Mr. Weast to concentrate on reform more than politics, and it provided both the resources and the time essential for such an experiment to take root.

Mr. Weast and the Montgomery schools still have a long way to go. High school performance in the county remains uneven, middle school performance even more so. But these second-grade test scores show that it is possible to raise teacher morale and student achievement, even in a school system whose population is changing as rapidly as that of Montgomery County. Others in the region should take note.