The purpose of the present study was to quantify the degree of heterogeneity of the DSM-III-R alcohol dependence category by comparing the number of potential subtypes of dependence to those empirically observed in a general population survey. Forty-one percent (n = 189) of the 466 potential subtypes of DSM-III-R alcohol dependence were observed, indicating that the category is indeed heterogeneous, but not as heterogeneous as theoretically predicted. Variations in the number, percent and configuration of empirical subtypes of dependence are discussed in terms of coincident morbidity, premature death from alcoholism or death from other competing causes, reporting biases and differences in drinking patterns. The predominance of the 'tolerance' 'withdrawal' and 'impaired control over drinking' criteria among the empirically observed subtypes of dependence are examined within the context of the physiological dependence subtype proposed for the DSM-IV category of alcohol dependence and difficulties encountered in operationalizing these diagnostic criteria. The relevance of study findings to the validation of diagnostic categories in psychiatry is also highlighted.