This report draws lessons from 30 states' implementation of existing optional Medicaid coverage for youth who age out of foster care and applies them to decisions and plans states will consider as they implement new ACA coverage that goes into effect in 2014. Wide variations in how states have implemented the socalled Chafee Option are focused on eligibility criteria, enrollment processes, and recertification processes. States' implementation choices had implications for the frequency with which youth enroll in Medicaid coverage after foster care and in their continuity of coverage over time.