Research investigating links between academic achievement and active music instruction has not previously differentiated between different types of instruction. In the current study, 155 seventh- and eighth-grade middle school band students were divided into two groups. Both groups received 2 months of instruction in jazz phrasing, scales, and vocabulary, but only the experimental group was taught to improvise. All instruction was part of the warm-up routine in regular band classes. All students were tested before and after instruction on the Wisconsin Card Sorting Task (cognitive flexibility) and the classic Stroop task (inhibitory control). At posttest, eighth-grade students in the experimental group scored significantly better on cognitive flexibility with a smaller percentage of perseverative errors, whereas the treatment had no effect on seventh-grade students on this outcome. Seventh graders, but not eighth graders, in the experimental group increased their posttest scores for inhibitory control, though this result was only marginally significant. In relation to previous research, the current results strongly suggest that far-transfer effects of active music participation depend on the nature of the instruction. Results of prior and future studies should therefore be interpreted in light of the type of music-making engaged by participants.