This article reviews over 50 years of research on teacher expectations and teacher effectiveness. In addition to describing these research traditions and findings, I tie the research in these evolving fields to the societal issues in play when the research was conducted and connect historical and emerging work. I describe the enormous growth of knowledge in both fields and its potential for practice. Among many outcomes, these two research traditions yielded clear evidence that teachers impact student achievement. Despite the potential value of this research, it has largely been ignored by policy makers, and when used, has been misused. I contend that policy makers have focused on the weaknesses of normative teaching and have ignored teachers' strengths and knowledge. Of course, aspects of normative teaching can be improved, as can teacher expectations and teacher effectiveness research. Current and continuing research has some capacity for addressing the opportunity and achievement gaps that separate more advantaged and marginalized students; however, teachers and schools alone cannot resolve these vast opportunity differences that are available to American students.