In the U. S., there is significant controversy about how teachers should be prepared and licensed. Many of the sharpest controversies stem from public skepticism about whether formal teacher preparation is necessary given the lack of conclusive evidence that it has a direct impact on students' achievement. This article presents a review of recent research that empirically examines the connection between teachers' education and either teaching practice or teacher retention (or both). The literature in six distinct genres of research is reviewed with cross-genre conclusions and implications.