The purpose of this study was to investigate the potential viability of the variable certification by the National Board for Professional Teaching Standards (NBPTS) as a policy-relevant predictor of student achievement. Because research has identified the teacher as the most important school-related predictor of student achievement, more research is needed with regard to teacher quality. Policy-relevant, measurable variables may help define teacher quality but fall short of addressing the complexity of teaching and learning. High quality teaching practice means effective application of subject content and pedagogical knowledge and skills consistent with student needs and research-based practices that advance student achievement within a specific classroom and school context. Using a sequential multiple regression, the study analyzed a random sample of 339 Kentucky schools and included school-level measures of teacher quality, student achievement, measures of student demographics, and assessed property valuation. Study results indicated four measures of teacher quality, to include National Board certification, were significant predictors of student achievement as measured by the CATS index. These results suggest that the variable percentage of teachers holding national board certification may be useful as an indicator of teacher quality. The identification of policy-relevant characteristics of teacher quality is critical for educational leaders in an era of accountability. Because teacher quality must be defined by practice, NBPTS certification offers possibilities as a variable to assess not only what teachers know but also what they do in the classroom to promote student learning. (Contains 2 tables and 1 figure.)