Like other states, North Carolina maintains a system of certification and licensing for public school teachers. Proponents of the system argue that certification standards will separate good teachers from poor ones, but there is no evidence that these standards determine teacher quality. A state-by-state comparison of teacher certification and student performance on the most recent National Assessment of Educational Progress (NAEP) mathematics exam shows that certification standards and teacher testing did not improve test scores. Schools should be able to recruit and retain talented teachers whether they are certified or not.