In our efforts to ensure that every student receives top-quality teaching, we have made substantial progress in understanding the links between teacher practice and student learning—the technical side of teacher assessment. But we have too often overlooked the human side. Also, we have not fully appreciated the crucial role that district leaders play in establishing the relational climate that can make or break schools' efforts to improve teacher quality.

Research on teaching largely addresses the measurement of teacher effectiveness. Models of teacher performance assessment apply this research to district supervision and evaluation policies. Although these findings are vital to successfully assessing teacher performance, a technically valid and reliable assessment framework will not by itself ensure the improvement of teaching.