The most popular measure of tobacco dependence, the Fagerstrom Tolerance Questionnaire (FTQ), measures only tobacco-specific behaviors. In contrast, the most popular assessment of addiction among polydrug users is the Addiction Severity Index (ASI). Most of the subscales comprising the ASI are psychosocial measures, not drug-specific measures. A study was undertaken to compare the predictive utility of these two contrasting measures. The NAS (adapted from the FTQ) and the Addiction Severity Index (ASI) were used to predict future smoking status in a cohort of polydrug users followed annually for 3 years. The baseline NAS score explained more of the variance in Time 2 and Time 3 smoking status than did the ASI subscales. When previous smoking status was included as a covariate, however, the NAS no longer predicted future smoking status, whereas the ASI Subscales continued to explain significant variance in future smoking status. Results suggest that when past smoking behavior is known, a respondent''s legal status and alcohol use may be more useful than a measure of tobacco dependence for predicting future smoking status.