Objective: Considering the importance of identifying the factors effective in substance use for the design of some interventions on addiction prevention and treatment, the present study aimed at examining the mediating role of emotional dysregulation in the relationship between impulsivity personality trait and consumption & multiple consumption of drugs, alcohol, and tobacco.Method: The number of 352 subjects was selected through convinince sampling method from among the 18-to-60-year-old population of Tehran city and were assessed by means of UPPS-P Impulsive Behavior Scale, Difficulties in Emotion Regulation Scale, and researcher-constructed questionnaires on substance use. The data were analyzed through correlation tests and structural equation modeling (SEM) in SPSS and Mplus software.Results: The results of this study showed that impulsivity dimensions and emotional dysregulation had a significant correlation with consumption & multiple consumption of drugs, alcohol, and tobacco. The proposed model had a good fitness index with the data; however, the effect of emotional dysregulation on substance use was not statistically significant. Sensation seeking (b=0.42, P<0.01) and lack of premeditation (b=0.46, P<0.01) had a significant effect on substance use; and lack of premeditation (β=-0.27, P<0.01), negative urgency (b=0.83, P<0.01), and lack of perseverance (b=0.13, P<0.05) had a significant effect on emotional dysregulation.Conclusion: Although both impulsivity dimensions and emotional dysregulation had a significant correlation with consumption & multiple consumption of drugs, alcohol, and tobacco, when they were used in one model, the impulsivity dimensions had a stranger effect on substance use and played a more prominent role in the anticipation of substance use.