A statistical analysis was conducted to examine changes across time in some school districts of Pennsylvania. Comparisons were made for grades 5, 8, and 11 during two assessment periods. The Educational Quality Assessment data provided the basis for analysis. Correlation coefficients for school mean goal scores are displayed. Changes at the three grade levels are presented in table format. The reasons for differences across time are elaborated, e.g., there were differences in classes of students in terms of ability levels and attitudes that influenced achievement. Several factors which accounted for differences in the composition of classes are delineated: differences existed in test administration conditions or procedures from one assessment to another; the number of students at each grade level assessed varied; and there were differences in instructional programs and school climate for various reasons. These differences were also observed in standardized test scores. (DWH)