Several striking differences in the frequency of crack use and dealing emerged among the various drug user types. Crack abusers were found to be using drugs at high rates and were receiving high incomes from drug sales and nondrug criminality. Among crack abusers, crack use greatly exceeded the cost and frequency of use of other specific drugs, which they were also consuming. For all user subgroups, crack selling was the most frequent crime and generated the largest cash income. Important patterns of polydrug use were found among most drug user groups. This continuity of abuse across drug types may suggest that control policies should focus on the drug problem in general, rather than on one specific drug. Seeking to control crack, for example, may result in the emergence of a new drug. On the other hand, the consequences of the crack epidemic have been so far- reaching that it may need to be directly addressed. Crack abusers have higher intensities of use than most other drug abusers and the cost and frequency of crack use is much higher than for any other drug. 9 tables and 38 references