Background: Adults with intellectual and developmental disabilities and their families have high need for support services. This study assessed resource utilization among caregivers of intellectual and developmental disabilities and other conditions. Methods: We assessed 366 caregivers of adults with intellectual and developmental disabilities, dementia or other conditions Regressions assessed group differences in number of agency contacts and frequency of service use. A secondary analysis assessed reasons for underutilization of services. Results: Caregivers of individuals with dementia contacted twice as many agencies as other caregivers and were more likely to report using suggested services. Agency contact and service utilization were similar among caregivers of adults with intellectual and developmental disabilities compared to other caregivers. Caregivers of adults with intellectual and developmental indicated that suggested services were unavailable to them. Conclusion: The findings of this study shed light on challenges with access to and utilization of support services.