Teacher quality has been found to offset the adverse effect of racial and socioeconomic differences in academic achievement; and teacher quality is often thought to be the product of a quality education. However, existing literature has produced mixed results regarding the relationship between student achievement and teachers’ possession of advanced degrees (ADs). Despite these mixed results, ADs are often the most efficient (if not the only) way for teachers to earn certification and salary upgrades. A longitudinal, multiphase mixed-methods explanatory study aimed to bridge shortcomings of existing research on the effects of teachers obtaining ADs. Associations between teacher credentials and middle grades students’ academic growth were examined by differentiating teachers’ degree level (bachelor’s, master’s, specialist’s) and field (content-related, non-content-related). Teachers and school leaders were also interviewed in order to broaden our understandings of the impact ADs make in areas besides student achievement. Findings suggest that inconsistency in associations between teacher ADs and student achievement may be attributable to variation in a number of individual, programmatic, and institutional factors.