Questions about usual drinking play an important role in the construction of alcohol consumption measures. However, little is known about difficulties in answering these questions for respondents with variability in their drinking patterns. We investigated this in a community sample of 945 drinkers and in a clinical sample of 400 patients treated for alcohol and/or drug problems. Demographic variables were not consistently related to self-reported difficulty in answering, but a diagnosis of current DSM-IV alcohol dependence was significantly related in both samples. In modeling the relationship between alcohol consumption and DSM-IV alcohol dependence, the fit of the model to the data was significantly improved by the addition of a variable indicating respondents' difficulty answering the usual drinking questions. Using this information in the development of alcohol consumption questions may provide more precise estimates of the risk from alcohol consumption to outcomes such as alcohol dependence.