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.