Survey results have suggested that, while teachers like to have test information available, most do not have great skill or consistency in interpreting test score data. Teachers who consider a certain type of test very valuable or useful are less likely to question the accuracy of the scores than are teachers who consider a test to be of little value. Also, teacher judgments of test score accuracy are apparently tempered on the basis of other information. The overall intent of the project described in this report was to learn more about how teachers perceive test score data; how they use test and nontest data in decision making; factors which might be related to knowledge or perception of test score data; and whether knowledge or perception of test score data can be changed through brief instruction. Reported are six studies that were conducted, focusing on: (1) teachers' perceptions of test score accuracy; (2) teachers' interpretations of pupil performance record; (3) teachers' interpretations of point and interval score estimates; (4) teachers' estimates of costs and losses in decisions; (5) factors influencing teacher estimation of pupil performance; and (6) changes in teachers' knowledge and perceptions of test score data. A description is given of the methodology used, the results, and an interpretation of findings for each of the tests. Appendixes include instruments used in the studies and tables of results. (JD)