Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 11 4 2016 12 31 244 249 EN Manoochehr Azkhosh University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Ali Farhoudianm Substance Abuse and Dependence Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. hemn saadati Substance Abuse and Dependence Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Fateme Shoaee University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. leila lashani Student Research Committee, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. 2016 01 27 Objective: Substance abuse is a socio-psychological disorder. The aim of this study was to compare the effectiveness of acceptance and commitment therapy with 12-steps Narcotics Anonymous on psychological well-being of opiate dependent individuals in addiction treatment centers in Shiraz, Iran. Method: This was a randomized controlled trial. Data were collected at entry into the study and at post-test and follow-up visits. The participants were selected from opiate addicted individuals who referred to addiction treatment centers in Shiraz. Sixty individuals were evaluated according to inclusion/ exclusion criteria and were divided into three equal groups randomly (20 participants per group). One group received acceptance and commitment group therapy (Twelve 90-minute sessions) and the other group was provided with the 12-steps Narcotics Anonymous program and the control group received the usual methadone maintenance treatment. During the treatment process, seven participants dropped out. Data were collected using the psychological well-being questionnaire and AAQ questionnaire in the three groups at pre-test, post-test and follow-up visits. Data were analyzed using repeated measure analysis of variance. Results: Repeated measure analysis of variance revealed that the mean difference between the three groups was significant (P<0.05) and that acceptance and commitment therapy group showed improvement relative to the NA and control groups on psychological well-being and psychological flexibility. Conclusion: The results of this study revealed that acceptance and commitment therapy can be helpful in enhancing positive emotions and increasing psychological well-being of addicts who seek treatment. https://ijps.tums.ac.ir/index.php/ijps/article/view/606 https://ijps.tums.ac.ir/index.php/ijps/article/download/606/582