To explain the discrepancy between median scores on the 1976 administration of the California Achievement Tests (CAT) and the Sequential Tests of Educational Progress (STEP) in the Austin Independent School District (AISD), ten technical variables typical of achievement tests were considered as explanations. (1) The STEP may measure different skills than the CAT. (2) Norm groups may differ. (3) The STEP may not measure what the high schools are teaching. (4) Curriculum sequencing of AISD high schools may not conform to that of the norm group. (5) Cross-level curriculum planning between elementary, junior high, and senior high levels may not be coordinated. (6) The AISD population may differ from the national population and hence from the norms. (7) Test familiarity may play a role in score differences. (8) The STEP is a more difficult test than the CAT. (9) The time of year of the administration may have depressed STEP scores. (10) Administration procedures differed from those used in the norming study. Of the ten variables considered, all but number 3 and possibly number 4 were accepted as possible explanations for the score differences. A further comparison was made between the CAT, STEP, and the CTB/McGraw Hill Proficiency and Review Tests for Reading and Numerical Proficiency. (CP)