Emotion dysregulation and social dysfunction are core characteristic of many psychiatric disorders such as schizophrenia and mood disorders. Medication-based treatment for patients with psychiatric disorders may alleviate acute clinical symptoms; however, it is limited in terms of its ability to improve social and emotional functions. There is evidence highlighting the central role of emotion regulation deficits in determining social functioning in individuals with psychiatric disorders. Therefore, emotion-related training intervention is needed to enhance patient's awareness and expression of emotions and for successful social functioning.Aim: the aimof this study was to evaluate the effect of an emotion regulation training intervention on social functioning of patients with psychiatric disorders.Setting: The present study was conducted at psychiatric inpatient department of TantaUniversity Hospital that is affiliated to Tanta University. Subjects: 60 patients with psychiatric disorders divided randomly into experimental and control group (30 patients in eachgroup).Tools:Difficulties in Emotion Regulation Scale and Social Functioning Scale were used to collect the study data. Design:A randomized controlled trial was conducted. The intervention was conducted through 9 training sessions, each session lasting from (60-90) minutes; 3 times per week for a period of 4 weeks. Results: there was a statistically significant improvement in social functioning and emotion regulation in the experimental groupthan the control group after the implementation of the intervention. Also, a statistically significant negative correlation was found between emotion regulation difficulties and social functioning.Conclusions :Emotion regulation training intervention has a salient effect on reducing emotion regulation difficulties and improving social functioning in patients with psychiatric disorders. Recommendations: this non-pharmacological evidence-based-nursing practice should be incorporated in the psychiatric hospital protocol for cumulative and consistent effects