What is the impact of New Hampshire's modified prospective payment system for Medicaid inpatient psychiatric services on access to care and costs? In 1989, New Hampshire adopted a new system of paying for inpatient psychiatric services for Medicaid beneficiaries which divides psychiatric facilities into three groups and pays hospitals in each group a prospective rate per Medicaid admission based on the average costs for facilities in the group. This study, conducted by Boston University, used Medicaid claims data and state discharge data from FY 1988-1992 to assess hospital response to the payment change (including changes in average length of stay, and volume and type of clients admitted), the likelihood of admission to various types of facilities, whether certain types of Medicaid patients experience difficulty in gaining access to inpatient psychiatric care and the impact on state psychiatric service costs. They sought to determine whether this prospective system could be adopted successfully by other state Medicaid programs, the Medicare program, or private payers of psychiatric services.