This course consists of five major sections. We discuss definitional issues next, followed by a general discussion of teachers’ assessment practices. The third section focuses on a series of studies designed to improve teachers’ assessment techniques and the influence of such professional development on instruction, as well as school and district uses of data. In the fourth section, we consider the organizational conditions that are described in the numerous articles on teachers’ assessment practices. The closing section considers the potential areas for future research emerging from the course.