States and districts have launched unprecedented efforts in recent years to build new feedback and evaluation systems that support teacher growth and development. These systems depend on trustworthy information about teaching effectiveness--information that recognizes the complexity of teaching and is trusted by both teachers and administrators. To that end, the Measures of Effective Teaching (MET) project set out three years ago to investigate how a set of measures could identify effective teaching fairly and reliably. With the help of 3,000 teacher volunteers along with scores of academic and organizational partners, the researchers have studied, among other measures: (1) Classroom observation instruments; (2) Student Perception surveys; and (3) Student achievement gains. This final brief from the MET project's three-year study highlights new analyses that extend and deepen the insights from the researchers' previous work. These studies address three fundamental questions that face practitioners and policymakers engaged in creating teacher support and evaluation systems. (Contains 5 figures, 1 table, and 10 endnotes.)