Whereas the model of Jellinek [Q. J. Stud. Alcohol 7 (1952) 673] of a predictable progression of alcoholism is generally supported, there have been few published studies regarding the natural history of illicit drug disorders. Identification of the development of drug abuse and/or dependence can inform clinicians and researchers on issues, such as diagnosis, prognosis, assessment, and prevention. This study employed a new measure adapted from the 46 events described in Jellinek's progression of alcoholism. Nine licit and illicit substances were also included within the cardsort. Fifty-two individuals motivated to enter drug treatment by a loved one were assessed pretreatment. The drug initiation sequence reported by this sample was as follows: alcohol, tobacco, inhalants, marijuana, and then other drugs. Spearman rank correlation coefficients were conducted between the drug sample and that of Jellinek yielding a modest correlation (r=.35, P=.019). These results suggest that Jellinek's model of progression of alcoholism may also apply to the development of drug disorders. However, important differences found between the alcohol and drug progressions are discussed.