Summary: This report describes behavioral health service use and expenditures for Massachusetts Medicare and Medicaid (MassHealth) members aged 55 and over with behavioral health disorders (BHDs) in calendar year 2005. With an expected increase in the number of elders with BHDs, a better and more comprehensive understanding of behavioral health service delivery is essential in order to identify opportunities for systematic changes that can improve behavioral health services for elders. However, older adults have not been the main focus of previous studies on behavioral health services and expenditures. Furthermore, although existing studies have examined behavioral health services and expenditures in broad geographic areas and at the national level, few studies have taken into account variations among health insurance coverage, particularly Medicare and Medicaid which are important resources for elders and for people with disabilities.