The importance of teacher quality for determining student outcomes is now well established. At the same time, the translation of what is known about teacher quality into effective policy is far from being institutionalized. The simplest summary of research into teacher quality is that some teachers are dramatically more effective than others but that common measures of quality are largely uncorrelated with true quality. Thus, for example, we continue to face problems of insufficient numbers of high-quality teachers, or shortages of math and science teachers, and of "out of field" teachers. Many argue that we should tightened up on entry requirements along with increasing overall pay, but these policies are unlikely to deal with the current problems. Instead, we are likely to be much better off by loosening up entry requirements, by paying more attention to retention decisions, and by rewarding the people we want--those who are effective and who meet current areas of need. (Contains 16 footnotes and 1 figure.)