Now in a fully rewritten fourth edition, this is the authoritative presentation of motivational interviewing (MI), the powerful approach to facilitating change. It has been updated and streamlined to be even more user-friendly as a practitioner guide and course text. MI originators William R. Miller and Stephen Rollnick elucidate the four tasks of MI--engaging, focusing, evoking, and planning--and vividly demonstrate what they look like in action. A wealth of vignettes and interview examples illustrate the dos and don'ts of successful implementation in diverse contexts. The book reviews the evidence base for the approach and covers ways to assess the quality of MI. The companion website provides reflection questions, annotated case material, and additional helpful resources.