In this study, we used Andersen's Behavioral Model with the family as a unit of analysis to examine the patterns of awareness and utilization of social services by families with at least one adult with intellectual disabilities. Face-to-face interview questionnaires were conducted with primary family caregivers in Hsinchu City, Taiwan in 2004. Data were collected on adults' and caregivers' predisposing, enabling, and need variables as well as awareness and utilization of formal social services. A total of 792 interviews were completed, making a response rate of 94.2%. Multivariate logistic regression analysis was used to identify potential predictors of social service awareness and utilization. We found awareness and utilization to be mostly associated with predisposing and enabling variables including caregiver's socioeconomic status, family connection with social networks, and family participation in related groups or associations. Younger caregivers were more likely to access formal assistance, while adults whose families were more connected into social networks were more likely to be aware of in-kind and voucher services, e.g., in-home services including respite and home care, and vocational services such as sheltered workshops, and bus voucher services.