Teacher evaluation is receiving increasing attention. Texas is the largest state to adopt a statewide appraisal instrument. The purpose of this study was to examine differences in Texas Teacher Appraisal System (TTAS) scores over a period of four years. The sum of scores of the first four individual domains and the overall summary performance score for teachers in a large school district in central Texas for four years (1988-1989, 1989-1990, 1990-1991, and 1991-1992) were examined. Specifically, scores between appraiser types (primary or secondary), levels (elementary or secondary), and appraisal periods (first or second) across years were investigated. Overall, results showed that scores increased significantly over the four year period, there was a significant appraiser type effect (although significant differences between scores awarded by primary appraisers and second appraisers were not evident in the fourth year), there was no significant difference between elementary teachers and secondary teachers, and there was no significant difference between appraisal periods. (Contains 38 references and 5 tables). (Author)