Most teacher evaluation policies in the United States seek to improve student outcomes by providing developmental supports to grow teachers' skills and by imposing accountability pressures to increase their effort. In this research synthesis and analytic essay, David D. Liebowitz argues that proper policy design has been understood as successfully balancing the accountability and growth dimensions of teacher evaluation. He details six conditions that determine whether joint-aim teacher evaluation policies will improve student outcomes and assesses the extent to which they are likely to be met given the causal evidence from the education, economics, social psychology, and management research literatures. The article concludes with recommendations to more clearly delineate the accountability and growth aims of teacher evaluation.