Research on effective mechanisms of alcohol brief interventions has been neglected, but Bertholet and colleagues provide an example of such research in a re-analysis of combined data from 3 trials of brief motivational interviewing (BMI). However, it is disappointing that, in a well-designed and well-conducted analysis, little support was found for highly plausible hypotheses relating treatment processes to outcome of intervention. It is argued here that, because BMI must be assumed to work by increasing client motivation to cut down drinking, some measure of overall motivation before and after intervention is necessary to elucidate the pathway by which treatment processes are translated into positive outcomes. In pioneering research on physician advice on smoking cessation by Russell and colleagues, it was possible to distinguish between whether intervention worked by motivating more people to try to stop smoking, by increasing the success rate among those who did try, or by reducing the relapse rate among those who quit. It is recommended that similar measures be employed in research on how alcohol brief interventions work. A further consideration bearing on the relationship between treatment processes and outcome is whether or not individuals are dependent on alcohol and this is reminiscent of a dispute in the literature concerning the relative priority that should be given to motivational or dependence variables in the prediction of smoking cessation. In order to improve the effectiveness of alcohol brief interventions, future research should focus more on effective mechanisms of behavior change.