This review traces the development of motivational interviewing (MI) from its happenstance beginnings and the first description published in this journal in 1983, to its continuing evolution as a method that is now in widespread practice in many professions, nations and languages. The efficacy of MI has been documented in hundreds of controlled clinical trials, and extensive process research sheds light on why and how it works. Developing proficiency in MI is facilitated by feedback and coaching based on observed practice after initial training. The author reflects on parallels between MI core processes and the characteristics found in 70 years of psychotherapy research to distinguish more effective therapists. This suggests that MI offers an evidence-based therapeutic style for delivering other treatments more effectively. The most common use of MI now is indeed in combination with other treatment methods such as cognitive behaviour therapies.
Keywords: cognitive-behavior therapy; motivational interviewing; therapist effects.