The first in a series of long-awaited studies indicates that nationally certified teachers are more effective at raising their students' reading and math scores than are teachers who apply for the credential but do not receive it. Although critics have questioned the expenditure of state and district money on National Board for Professional Teaching Standards certification, the examination of hundreds of thousands of student test scores offers the first evidence that teachers who undergo the process make a difference in the classroom. Launched in 1987, national-board certification is a voluntary process of evaluations, portfolios, student work, and subject-matter tests that can take between one and three years to complete. This research, which focused on North Carolina, found that end-of-the-year test scores improved an average of 7 percent more for students whose teachers had earned the seal of approval from the national board, when compared with students whose teachers had failed to earn it. The study examined more than 610,000 state test scores of 3rd, 4th, and 5th graders over three school years, from 1996-97 through 1998-99. The results of this study indicated even more significant results for younger pupils and for children from low-income families. In reading, the difference in scores for students with board-certified teachers rose to 12 percent for 3rd graders, compared with their peers whose teachers did not earn the credential. Also in reading, the difference in scores for children who qualified for free or reduced-price lunches rose to 15 percent--confirming, the report says, the belief that teacher quality matters more for disadvantaged students.The researchers, however, do not conclude that the certification process itself creates teachers who are more effective. Whether board-certified teachers have an influence on student achievement, the authors of the study write, depends on their career paths.