For approximately 14 consecutive days every quarter, St. Louis personnel obtain voluntary and anonymous interviews and urine specimens from a sample of booked arrestees who have been in custody for no more than 48 hours. The sample of the current study consisted of 1,580 adult St. Louis arrestees interviewed from the first quarter of 1996 through the third quarter of 1997. Urinalysis results were used to validate self-report measures of substance abuse. The analysis shows not only that drug-using classifications differed between criminal and non-criminal populations, but that arrestee populations varied interjurisdictionally. The classifications identified in St. Louis were considerably different from those identified in Philadelphia and San Jose. Two possible explanations are offered for these differences. First, consistent with the previous literature on drug-using classifications, all individuals (criminal or non-criminal) vary in their characteristics. A second more salient explanation for the differences among ADAM populations is geographic location. Consistent with ADAM findings, arrestees in the Midwest use different types of drugs than East Coast or West Coast arrestees. Suggestions are offered for future research in this area. 4 tables and 31 references