Given the important roles of family caregivers and the likelihood that individuals with IDD will live in their family homes into adulthood, it is crucial to examine adult service delivery systems within the context of families of individuals with IDD. In this manuscript, we aim to describe the adult service delivery system, specifically with respect to HCBS Medicaid waiver in the United States, and its relation to the contexts and implications of family caregivers for adults with IDD. We begin by providing a history of adult services; then, we shift our focus to community-based support. Next, we discuss the theoretical framework, Family Systems Theory. Then, we describe the contexts and implications of family caregivers. We conclude with directions for future research, practice, and policy. Because this manuscript highlights the complicated nature of adult services, we provide a description and list of the relevant acronyms in Table 1.