Although nearly 200 million has been invested in producing and rewarding National Board-certified teachers, a study by Lloyd Board and colleagues is the first to assess whether such teachers perform better than their peers. It is uncertain whether researchers' 13 measures of teacher expertise actually correlate with improved student achievement.…

Articles in this special issue deal with the assessment of the impact of research and are divided into segments concerning semiquantitative approaches; qualitative approaches; and quantitative and fiscal approaches. These articles illustrate the importance of the role of motivation and associated incentives. (SLD)