The goal of this project is to help inform policymakers and other stakeholders engaged in debates about Medicaid funding and administration. Over the course of the Great Recession, Arizona addressed significant budget shortfalls by freezing enrollment in its Medicaid program twice: first in December 2009, to KidsCare, the State Children’s Health Insurance Program; and second in July 2011, to the “Proposition 204” program, which serves low-income, childless adults. Together, these enrollment freezes led to an estimated loss of more than 4.6 million member-months of health insurance coverage between 2010 and 2014. The Medicaid expansion made possible by the Affordable Care Act lifted the Proposition 204 enrollment freeze. In this study, the researchers will examine the impact of both enrollment freezes on emergency department visits and inpatient stays for ambulatory-care-sensitive conditions on the KidsCare and Proposition 204 populations, and evaluate the impact of regaining coverage on health care utilization and costs among those affected. Deliverables will include a project work plan, final narrative, and financial reports. The grantee will also produce paper(s) suitable for publication and present findings at national research meetings and to other stakeholder audiences as appropriate, including policymakers at the federal, state, and local levels, as part of the deliverables for this grant.