Carol L. Smith is a Professor in the Department of Psychology, University of Massachusetts Boston, where she has been since receiving her Ph.D. in Developmental Studies from Harvard University in 1976 and completing postdoctoral research at M.I.T in 1978. She is a cognitive developmental psychologist whose work on conceptual change in science education exempliﬁes part of the research basis for learning progressions. Over the past 30 years, she has studied the conceptual changes that occur as children develop their ideas about matter as well as their ideas about scientiﬁc models and knowledge construction in science. She has also collaborated with teachers, scientists, and science educators to create innovative teaching units for elementary and middle school students and to study their effectiveness in facilitating conceptual restructuring compared with more traditional teaching approaches. More recently, she worked on a team that synthesized current research in order to propose a long-term learning progression for matter (Smith, Wiser, Anderson, & Krajcik, 2006) and served on the National Research Council’s Committee on Science Learning, K-8, which authored Taking Science to School (2007). She is currently collaborating on analyzing data from two longitudinal studies—one with elementary school students (on matter) and the other with college students (concerning their conceptions of science).