Many states and districts are moving toward more targeted compensation policies as a way to attract higher quality candidates into the teaching profession and to encourage increases in productivity among current teachers. Rather than align pay increases only to level of education and years of experience, for example, many school systems have started to tie pay increases or bonuses to National Board Certification (NBC). But the practice has been questioned, in part because of a lack of empirical evidence that NBC is an effective signal of teaching quality. The present study uses data from a large urban school district to examine the association between student gains in mathematics in the ninth and tenth grades, NBC, and other indicators of teacher quality. Based on a variety of different specifications and student subsamples, we find robust evidence that NBC is an effective indicator of teacher quality.