Motivational interviewing (MI) is an empirically based practice that provides counselors with methods for working with resistant and ambivalent clients. Whereas previous research has demonstrated the effectiveness of training current clinicians in this evidenced-based practice, no research has investigated the efficacy of teaching MI to counselors-in-training who work with clients from the general population. The authors examined the effect of a student-based training in MI for 43 graduate-level counselor trainees using a quasi-experimental controlled design. Statistical analyses based on pretest and posttest assessments revealed participants' knowledge and skill in MI significantly improved in the treatment group. Implications for training future counselors and suggestions for additional research are explored.