A clear and consistent finding of educational research has been the importance of active student responding. During lectures and discussions, active responding most often takes the form of student responses to teacher questions. This whole group responding to questions, however, does not permit every student to respond and does not assure that all students are actively engaged. Previous research has shown that Numbered Heads Together is an efficient and effective instructional technique to increase student responding and to improve achievement. Using an A-B-BC-B-BC design, we examined the effects of two versions of Numbered Heads Together on 6th graders daily quiz scores and pretest-posttest performance in chemistry. Findings indicated that the addition of a behavioral incentive package noticeably improved student performance during Numbered Heads Together instruction. Implications are discussed for teachers and educational researchers.