Data from the Substance Abuse and Mental Health Services Administration's Integrated Database (IDB) were used to examine the service use patterns of individuals with possible opiate use disorders in Washington State. Results indicate that regardless of Medicaid enrollment status, individuals who received mental health (MH) or substance abuse (SA) services only through state agencies received no inpatient substance abuse service. Furthermore, when compared with individuals who received at least one MH/SA service through Medicaid, those who received services only through the state agencies were less likely to have received any MH services and were more likely to have received residential SA services. This analysis highlights the importance of using integrated client data in providing a more comprehensive understanding of services to inform policy and raises significant questions about how regulatory requirements affecting different funding mechanisms might drive settings of care in ways not related to the care needed.