Objective: This study was conducted to compare the environment of families with and without substance-dependent members to investigate the functioning of families with substance-dependent members and also provide them with appropriate treatment strategies. Method: A causative-comparative method followed by an ex post facto design was used in this study. A sample of 50-person suffering from substance-dependent disorder referring to outpatient treatment centers, located in west and east of Tehran, constituted the participants of the study. As well, another 50-person group not suffering from the disorder participated in this study as the former group’s counterpart. The participants answered the questions of environment of family scale (EFS) (Moos d Moos, 1986). Findings: The results showed that there was a significant difference between two groups in dimensions of cohesion, conflict, achievement orientation, intellectual-cultural orientation, religious orientation, organization, and control whereas therewas no significant difference between the two groups in dimension of expressiveness, independency, and recreational orientation. Conclusion: The study recommends the authorities the application of efficient interventionist treatment strategies appropriate to the characteristics of families having drug-dependent member.