Introduction: The goal of this study was to examine socialization in adults with intellectual disability in relation to gender, level of intellectual disability, mental illness, and setting type. Methods: The sample consisted of 120 participants (60 males and 60 females), aged between 20 and 56 years, divided into two groups: 1. participants with intellectual disability without the diagnosis of mental illness (ID only) and 2. participants with dual diagnosis (intellectual disability and mental illness). Socialization subscale from the Vineland Adaptive Behavior Scale was used for the assessment of socialization. Results: Level of intellectual disability and mental illness had significant effects on socialization scores. In addition to this, interaction effect of gender and level of intellectual disability had a significant effect on socialization. Setting type did not have a significant effect on socialization. Conclusion: These results can be very useful in identifying participants with intellectual disability who might need additional individualized support programs in the area of socialization.