This study sought to determine whether an in-service program would produce changes in teacher attitudes and in teacher-student verbal interaction in the classroom and whether the amount and direction of this change could be significantly measured. During an 8-week in-service program, an experimental group of 10 English and 10 mathematics teachers from the Spring Branch Independent School District constructed and utilized an instrument for coding teacher-student verbal behavior in their classrooms; experimental and control classroom sessions were taped and coded; and teachers responded to attitude inventories. Conclusions indicated that (1) an in-service program designed to aid teachers in becoming more effective in their verbal behavior in the classroom did change teacher-student verbal interaction, and (2) an in-service training program in teacher-student verbal interaction, at least as indicated in the attitude inventories, did not seem to change the attitudes of teachers in the project. (Author/JB)