Although it is well-known that individuals with intellectual and developmental disabilities (IDD) are socially vulnerable, the field lacks valid assessments to identify risk factors for victimization. Parents/caregivers of 428 individuals with IDD (ages 12-53) completed the social vulnerability questionnaire (SVQ), a measure developed to assess specific aspects of social vulnerability among individuals with various forms of IDD. This study examined the psychometric structure of the SVQ (exploratory and confirmatory factor analysis), and the utility of the factors of the SVQ as predictors of diagnostic category (through discriminate function analysis). Results provide psychometric support for use of the SVQ and its factors for further research and as part of a clinical assessment battery to assess social vulnerability and to develop interventions.