Motivational interviewing (MI) is an effective method of promoting change in adults, but research on adolescents is limited. This study tests the efficacy of MI for promoting academic achievement in middle school students. Participants were 103 6th-, 7th, and 8th-grade students randomly assigned to either a MI (n = 50) or a waitlist control condition (n = 53). Students in the MI condition participated in a single MI session during the 7th or 8th week of the second semester. In comparison to the control group, students who received MI demonstrated significant improvements in their class participation, overall positive academic behavior, and significantly higher 4th quarter math grades. Thus, consistent with other studies finding single session effects of MI, a single MI session can have beneficial effects on academic behaviors. Pending further study and replication of these findings, MI could become an efficient and effective new counseling approach for improving academic performance.