Verbal report procedures, such as interviews, tests and questionnaires, have become the dominant method to obtain clinical data on alcohol abuse and its modification through treatment. The extent to which this method provides reliable and valid information for research purposes, and how its accuracy and usefulness can be enhanced, is examined. A review of methodological studies in the alcohol literature shows that although the information obtained from alcoholics and heavy drinkers tends to be reliable and valid, there can be considerable variability in accuracy, depending on the sensitivity of the information sought, the specificity of the validation criteria, the personal characteristics of the respondents and the demand characteristics of the task. It is suggested that the question of whether verbal report procedures are valid or invalid is less important than the issue of how they can be improved to the point that confidence can be placed in their findings. To facilitate this process, methodological techniques likely to enhance validity are reviewed.