Psychoanalytic theorists concerned with substance abuse suggest that the affect tolerance and affect expression of addicts are impaired due to preverbal influences. However, psychoanalytic contributions have largely been limited to clinical speculations and case study reports. The present study investigated the hypotheses that opiate abusers will demonstrate more impaired affect tolerance and affect expression than cocaine abusers, and that both groups would appear more impaired than a sample of normals. To investigate these hypotheses, a recently developed instrument, the Epigenetic Assessment Rating System (EARS), was employed. The EARS empirically measures verbal and preverbal phenomena theoretically linked with stages of development. The subjects were 25 opiate, 25 cocaine abusers, and 25 normals, matched according to age, gender, and SES criteria. Results supported the hypotheses that opiate and cocaine abusers' affect tolerance and affect expression were significantly impaired as compared to normals. Although affect tolerance did not distinguish between opiate and cocaine abusers, affect expression did. Cocaine abusers were less impaired than opiate abusers by preverbal modes of affect expression, although under stress cocaine abusers regressed to similar states.