Educators believe that rather than being a mere possibility to improve as teachers, it is always "necessary" to improve. One way of improving teaching is to adopt teaching methods that are based on or supported by evidence of success in enhancing student learning. Most teachers base their instructional practices on tradition, the opinion of experienced practitioners, ideology, faddism, marketing, politics, or personal experience gained through trial and error. This article reviews the current status of university teaching and provides an overview for the need for evidence-based teaching. It describes problems with defining evidence as well as distinctions among systems of teaching and specific teaching actions. (Contains 1 table.)