A half century ago, in his 1964 address to the Associated Organizations for Teacher Education, Nate Gageknown to many as the father of research on teachingmade an impassioned plea for research on and for teacher education (Gage, 1964). On the heels of James Bryant Conant's (1963) review of teacher education, published less than a year earlier, Gage sought to shed light on how to strengthen the enterprise that Conant had so roundly critiqued. Harkening back to the Flexner Report that transformed medicine, Gage made the assertion that the practice of teacher education was generally stronger than medical education's had been at that time but that the scientific knowledge base to inform teacher education was much thinner.By this he meant both research about effective teaching that could inform the content of teacher education (research for teacher education) and research about the results of different approaches to recruiting and preparing teachers that could inform how teachers are educated (research on teacher education).The lack of research was not, in his view, for want of interest: Gage (1964) noted from his review, "Over the years, research on teacher education has at least been yearned for, even if too little of it has been done" (p. 1). At the same time, Gage noted that many dismissed the cause of knowledge for teaching, convinced that educational know-how was really nothing more than common sense. To make his point, he outlined a number of commonsense findings from education research; for example, that a teacher should subtract pretest scores from posttest scores in a given domain to find out how much children have learned from instruction and that generally, doing so will show that brighter children have gained more than others from that instruction. In addition, to strengthen a kind of behavior, it should be rewarded, and to eliminate a kind of behavior, it should be punished. He then went on to note that each of these obvious findings was, in fact, the exact opposite of what education research had found, making the case that what teachers need to learn in order to be effective is often far from intuitive.Recognizing that new approaches to major problems typically bundle many changes into one reform, Gage called for new methodologies beyond the then popular correlations of discrete teaching behaviors with outcomes of interest. He noted that if Using five AERA presidential addresses over the past half century as landmarks, this essay traces the evolution of research on teaching and teacher education as well as some critical impacts the research has had on policy and practice related to teacher education and teacher evaluation in the United States. The discussion shows how these addresses both reflected the progress and challenges of research on teaching and teacher education at the times they were delivered and identified paths that the education research community could take to address the challenges. It traces key influences of these lines of work on the quality of teacher preparation, assessment of teac...