Many commonly used definitions of alcoholism share four elements: excessive intake, mental disturbance due to drinking, disturbance of social and economic functioning, and loss of control over drinking. Eleven indices of drinking problems were constructed to represent these definitional elements and a prevalence estimate for each is presented. The indices include 3 indicators of excessive intake, 5 measures of interpersonal problems due to drinking, an index of the use of alcohol for coping with tension or anxiety, an index of possible alcohol addiction, and a description of the individual's own possible concern about his drinking. The data are taken from a longitudinal study of the uses of alcoholic beverages among ·the noninstitutionalized adult population of San Francisco, Calif. The sample (weighted N= 991), drawn by area probability techniques, makes possible the estimation of the prevalence of various drinking problems in a general population. For any one or more of the 11 indices, the rate was 6.2% (men 9.5%, women 4.0%). Various combinations of the 11 indices, approximating operational formulations of some widely known definitions of alcoholism, are presented and the associated prevalence estimates are shown to vary greatly according to the particular indices chosen to represent the conceptions of the nature of drinking problems. In all cases the rates for men exceed those for women, although the ratio of men to women varies with the nature of the index. Rates among women were more nearly equal to those among men for such problems as excessive intake and the use of alcohol to cope with anxiety and other states of tension. Men had much higher rates than women on all indices relating to trouble with other persons and agencies attributed to chinking. Substantial differences in apparent rates of drinking problems are introduced when the criteria of recency and severity required to include a case in making a prevalence estimate are altered. In the present study, a problem must have occurred in ·the year preceding data collection for the case to be counted as current. Similarly, the variation in apparent rates that can be attributed to the level of severity required for case inclusion is great. Some data are presented to illustrate the magnitude of differences that result from different (arbitrary) choices of criteria. It was noted that prevalence rates based on elements common to many definitions of alcoholism can be useful to researchers who hold differing conceptions of the nature of alcoholism. However, comparisons between studies which would be of great value are made difficult by the variations in apparent rates due to use of different problem indicators. This suggests that a standardized approach to measuring prevalence would greatly improve comparative studies.