The recent National Research Council (NRC) report, "Knowing What Students Know: The Science and Design of Educational Assessment," suggests that it is time to rethink the basic assumptions underlying assessment of students and the use of measurement data to enhance teaching and learning. This essay draws on arguments developed in the NRC report to consider why change is needed and how contemporary knowledge and information technologies can bring about the necessary and desired redesign of educational assessment. Expectations about what students should learn have changed in response to social, economic, and technological changes and as a result of the standards-based reform movement. This has resulted in increased testing, although current assessment systems are generally the product of outmoded theories and are characterized by the underuse of technology. Merging research on cognition, measurement, and technology suggests directions for revamping assessment practices to use assessments to inform teachers about the nature of student learning. Powerful information technologies will become as ubiquitous in education as they are in other settings, especially in the design of learning environments. Developing and implementing assessments that take advantage of new technologies will be expensive, but these costs represent an investment in education and the future. (SLD)