The findings from two large metropolitan jail systems (King County, WA and Pinellas County, FL) suggest that jail detention had little impact on the Medicaid status of detainees with severe mental illness, actually most cycled in and out of jail so quickly that their Medicaid benefits were not disrupted. The stated policy in many States is to terminate Medicaid benefits upon incarceration, but termination occurred for only 3 percent of the detainees enrolled in Medicaid in each county. Ninety-seven percent of those with Medicaid at jail entry were released with Medicaid intact after being detained, on average, approximately 2 to 3 weeks. Most of the detentions in this study did not exceed 1 calendar month. This report presents findings from a survey of State Medicaid agency directors who identified disenrollment policies for jail detainees and from an analysis of administrative data from two large urban counties that documented the extent to which jail detainees with severe mental illness were actually disenrolled. Tables, references