The Verbal Reaction Behavior Log (VRBL) is an instrument used for identification of teacher and pupil verbal behavior. The purposes for its use are (a) an increase in pupil-teacher interaction, (b) an enhancement of indirect and pupil-centered instruction, (c) focus of attention on the logic of classroom discourse, and (d) increased use of positive reinforcement in the classroom situation. The three major verbal or instructional categories in the VRBL are cognitive, skill, and affective. These are subcategorized into (a) concepts and/or facts, (b) classifications, (c) applications, (d) directions, (e) repetitive practice, (f) varied practice or performance, (g) personal involvement, (h) positive reinforcement, and (i) negative reinforcement. Research on the VRBL has emphasized the stability of the three major categories and modification of student-teacher behavior in desired directions using both VRBL and Flanders Interaction Analysis. Research has also examined the relationship between verbal behavior and pupil achievement. Results show that verbal behavior has had a significant effect on student achievement. (Six references are included along with a copy of the VRBL.) (BRB)