Advanced certification through the National Board for Professional Teaching Standards (NBPTS) is an effective way to identify highly skilled teachers, according to a congressionally mandated report from the National Research Council. Students taught by NBPTS-certified teachers make greater gains on achievement tests than students taught by teachers who are not board-certified. However, it is unclear whether the certification process itself leads to higher quality teaching. "Earning NBPTS certification is a useful "signal" that a teacher is effective in the classroom," said Milton Hakel, chair of the committee that wrote the report. "But we don't know whether the certification process itself makes teachers more effective--as they become familiar with the standards and complete the assessment--or if high-quality teachers are attracted to the certification process." The report recommends further research to investigate that question, as well as to determine whether NBPTS certification is having broader effects on the educational system. Studies suggest that many school systems are not supporting or making the best use of their board-certified teachers.