Reflecting on a career spent in assessment in personnel selection and managment, the author lists 12 things (items) that he wishes he knew about assessment. The first four items are underdeveloped ideas set aside because of the field's preoccupation with equal employment opportunity. A second set (items five through eight) comes from intellectual neighbors in other disciplines. Items 9 through 12 grew from pure frustration. The author wishes that he knew: (1) how to handle predictions of different criteria when predictions are inconsistent; (2) how to individualize assessments in making employment decisions; (3) what personality variations to assess for what kinds of performance problems, how they might be assessed, and what their assessment would add to the accuracy of predictors of performance or other job-related behaviors; (4) how to select teams or replacement members of existing teams; (5) what a "standardized" test really is; (6) whether excellence in measurement is really much better than excellence in non-metric assessment; (7) more about test-taking strategies; (8) more about program design and evaluation; (9) whether simulations and related content assessments really work and aid traditional aptitude assessments; (10) more about the physical demands of jobs; (11) why it is no longer assumed that decision makers have brains; and (12) how to handle those who do not recognize the need for improved assessment. Included are two tables, an eight-item list of references, and one flowchart. (SLD)