Theory and utility--key themes in evidence-based assessment: comment on the special section.

This article focuses on two key themes in the four featured reviews on evidence-based assessment. The first theme is the essential role of theory in psychological assessment. An overview of this complex, multilayered role is presented. The second theme is the need for a common metric with which to gauge the utility of specific psychological tests and measures for specific purposes. A metric from information theory is recommended. The implications of these themes for the four reviews and for the future of psychological assessment in general are discussed.