The National Board for Professional Teaching Standards[R] (NBPTS) has always welcomed scrutiny of the National Board Certification[R] process and the impact that National Board Certified Teachers[R] (NBCTs) have on teaching and learning. As a result, in the 20 years since NBPTS was founded, National Board Certification has become one of the most heavily researched areas in the teaching field. Scores of studies, research projects, and other reports have reviewed and evaluated various aspects of National Board Certification. These efforts have covered such areas as the impact of National Board Certification on student performance, the influence of the process on teacher retention, and the quality of assignments planned by National Board Certified Teachers. This report provides summaries of dozens of these studies. Overall, the studies show promising, but in some cases mixed, results regarding the impact of National Board Certification on student achievement as measured by standardized tests. The research is consistently positive about the influence of National Board Certification on teacher practice and morale, professional development, and areas of school improvement--such as leadership development, teacher mentoring, monitoring student performance, team-building, and curriculum development--that are critical to raising student achievement. A bibliography is included.