Psychometricians can and must learn from psychologists, and for several important reasons. One is that psychologists can enhance the ability of psychometricians to design assessments in substantively principled ways so that what test takers know is measured. A second is that psychologists can identify how test takers reason and how their knowledge and reasoning is influenced by situational factors and their background knowledge. In addition, psychologists are very aware of the diverse characteristics of the test takers who take assessments, and those characteristics have implications for assessment design and score interpretation. Finally, psychologists can help psychometricians provide useful and comprehensible information results from testing. The article begins by making some points about educational assessments and the work of psychometricians. It then describes why and how psychometricians can learn from psychologists. The article acknowledges that the recognition that psychological findings and perspectives are critical for a well-informed psychometrics has many precedents. It then identifies some limitations of current assessments before turning to a vision for improved assessments, including examples from work being done in psychology.