A clear consensus has emerged around the world concerning the desirability and even the urgency of basing health care delivery systems on evidence. Among behavioral health care providers such as psychologists, evidence-based practice (EBP) has been focused largely on interventions. Psychologists have long emphasized a scientifically based psychometric approach to the development of assessment procedures. Nevertheless, the era of evidence-based assessment highlights 2 somewhat different issues. First, sophisticated assessment is closely integrated with our emerging conceptions of psychopathology, rather than standing separate from these conceptions. Second, broad-based ongoing outcomes assessment systems are increasingly required for EBP on the part of governments and health care policymakers. This article summarizes these developments and looks to the future.