For almost a decade now, teaching and teacher education have been pivotal issues in state and national elections and legislation. In addition, there have been dozens of reports, surveys, blue-ribbon panels, research syntheses, professional initiatives, and new empirical studies examining the presumed relationships among teacher qualifications, teacher preparation, teaching performance, and educational outcomes. In short, it has become commonplace to presume that matters of teaching quality figure largely in the ultimate improvement of education. Despite this convergence of attention, it is important to note that there is often more than one question tangled up in debates about teaching quality. Three of the most important of these are: Does quality of teaching make a difference in students' learning and their lives? How do we define teaching quality? and How do we best recruit and prepare qualified teachers? In editorials for this journal and elsewhere, I have written extensively about the politicized debates that surround the third question regarding the preparation of qualified In this editorial, I touch briefly on whether or not teaching quality makes a difference and then concentrate on the issue of how we should define teaching quality. Does Teaching Quality Make a Difference? On this first question, there is enormous consensus. The American public, the education profession, researchers, legal advocates, and policy makers all seem to agree that quality of teaching makes an important difference in students' learning, their achievement, and their life chances. In a recent public opinion poll on teacher quality (Hart & Teeter, 2002), for example, it was clear that although the public strongly favored educational reform tied to accountability, they also equated educational improvement with quality teaching and were not willing to lower hiring standards to solve the teacher shortage problem. Along similar lines, even among those who argue for diametrically opposed approaches to teacher preparation, there is apparent consensus that teaching quality is a critical influence on how and what students learn. The frequency of citations by researchers and policy makers of all stripes to William Sanders's conclusion that individual teachers are the single largest factor that adds value to student learning (Sanders & Horn, 1998) makes this point persuasively. Finally, legal advocates in several pending cases across the country have consistently asserted that access to qualified teachers is a birthright of all children (American Civil Liberties Union, 2000). In short, despite different assumptions about the purposes of schooling, the nature of teaching as an enterprise, and appropriate ways to measure teaching effectiveness, there is enormous consensus that teaching quality makes a significant difference in learning and school effectiveness. The No Child Left Behind Act (NCLB) cemented this conclusion into law with its guarantee that all schoolchildren must have highly qualified teachers. How Do We Define Teaching Quality and Highly Qualified Teachers? On this second question, there is much less consensus. For the public at large (again based on the Hart-Teeter poll), communication, teaching skills, and a teacher's ability to interest students--rather than content information--are most important. When asked to define quality teaching more specifically, 42% of respondents mentioned designing learning activities that inspired pupil interest, 31% said having enthusiasm, and 26% said having a caring attitude, although only 19% mentioned having a thorough understanding of the subject. When asked to name the biggest problem preparing teachers, 67% said that developing the skill to make material interesting and accessible was a greater problem than developing content area knowledge. The public's emphasis on know-how and relating to students makes an interesting comparison to other definitions of teaching quality. …