Teacher experience has long been a central pillar of teacher workforce policies in U.S. school systems. The underlying assumption behind many of these policies is that experience promotes effectiveness, but is this really the case? What does existing evidence tell us about how, why, and for whom teacher experience matters? This policy brief distills the research on teacher experience into four general findings: (1) the effect of experience is most evident during the first few years of teaching; (2) the early-career experience effect varies by level of education and subject area; (3) inexperienced teachers are most likely to teach in high-poverty schools; and (4) the impact of experience differs for teachers in high- versus low-poverty schools. The brief concludes by discussing the implications of these findings for several key policy measures including teacher compensation, support and professional development, and the unequal distribution of teachers across schools.

National Board Certification (NBC) for teachers has become an important innovation in long-standing efforts to improve teacher quality. As states, districts, and teachers increasingly invest resources in this process, information is needed on its cost, impact, and value. This analysis estimates the full opportunity cost of four NBC support programs, examines how the cost burden is distributed, and compares the cost of NBC with the cost of the traditionally dominant approach for teachers' skill development and salary advancement: earning a master's degree. The study demonstrates that the application fee accounts for only 7--13 percent of the total cost of NBC. Costs are shouldered by a range of individuals and organizations, with the greatest burden on NBC candidates themselves. Our comparison with the cost of earning a master's degree suggests that NBC is the less costly approach, with implications for choosing among alternative resource investments to promote, recognize, and reward effective teachers.