This study examines the stability of teacher effectiveness over a two-year period and its relation to emphasized reading skills. Data gathered in 1974 and 1976 for all third-grade and sixth-grade reading teachers at an Indiana school identified teacher effectiveness in reading instruction, instructional emphases, and any trends that might have accounted for varying levels of pupils' reading achievement. The following conclusions were drawn: Teacher effect on pupils' reading achievement is stable over a two-year period. Elementary school teachers who are effective teachers of reading place greater emphasis on ongoing diagnosis, comprehension following reading, structured reading activities, and reading application. Elementary teachers who became more effective during the two-year period placed greater emphasis on these instructional elements than did those teachers who became less effective. (Author/RL)