Motivational interviewing: research, practice, and puzzles.

Motivational interviewing is a directive client-centered counseling approach for initiating behavior change by helping clients to resolve ambivalence. Background research that led to its development is reviewed, along with current evidence for its efficacy in reducing alcohol and other drug abuse. Elements of therapeutic style are briefly discussed. Although current evidence generally supports the effectiveness of motivational interviewing, the underlying reasons and mechanisms for change pose unsolved puzzles.