Study aim: Determining the effectiveness of acceptance and commitment therapy on reducing cravings and increasing psychological resilience in people with substance abuse Design: The clinical trial has an experimental and control group, with parallel groups, no blinding, randomized, and is conducted on 50 people. A random number table is used for randomization. Settings and conduct: The study is conducted on people with substance abuse in Ahvaz. 50 people with substance abuse are selected using a convenient and purposeful sampling method and according to the inclusion criteria. They are randomly divided into two intervention groups and a control group. The intervention is carried out in 8 90-minute sessions, one session per week for 2 months. Also, blinding is not performed. Participants/Inclusion and exclusion criteria: Inclusion criteria included: diagnosis of substance abuse or substance use disorder based on DSM-5-TR or diagnosis by a psychiatrist/psychologist, being between 20 and 50 years old, having at least 6 months of regular substance use history, and exclusion criteria included: having an acute psychiatric disorder or requiring hospitalization prior to the study, having a severe or debilitating physical illness, and taking psychiatric medications. Intervention groups: The intervention group includes people with substance abuse who receive 8 90-minute sessions, one session per week, under the intervention protocol of internal family system training. While the control group does not receive any intervention. Main outcome variables: Craving, psychological flexibility