Prochaska and DiClemente's Transtheoretical Model predicts dropout from substance-abuse treatment. However, it is not known whether readiness to quit smoking is associated with attrition from drug treatment programs with smoking restrictions. This study examined the relationship between smoking characteristics, smoking stage of change, and both length of stay (LOS) and discharge type among 75 perinatal substance abusers attending a smoke-free residential treatment program. URICA scores predicted LOS (P=.0004) and discharge type (P=.01). Women in action and maintenance remained in treatment longer and were more likely to complete treatment compared to those in precontemplation. Findings were not accounted for by addiction severity. Women with little interest in quitting smoking may have difficulty adhering to smoking restrictions during treatment for other drug problems, resulting in increased attrition. Alternatively, smoking stage of change may be a "proxy" for overall readiness to change in this population. © 2004 Elsevier Ltd. All rights reserved.