Over 30 million Americans are estimated to gain insurance coverage as a result of full implementation of the Affordable Care Act (ACA). Much of this increase in coverage will be driven by an expansion of Medicaid eligibility. Such an expansion of coverage leads naturally to several policy relevant questions: How should the health care system best respond to potential reductions in access to providers that may come about as a result of increases in demand for health care services? Would it make sense to increase provider funding? As an alternative, would it make sense to exploit more heavily the tools of managed care to better “manage” the care of the newly insured? Are there specific services whose expansion would lead to better health outcomes? How would these changes in a public program such as Medicaid impact the private market for health insurance? The four papers in this proposal use unique sources of data both from the United States and Chile to attempt to address these questions. These unique data sources include publically available national data from the National Health Interview Survey as well as confidential state Medicaid claims and enrollment data. Clearly the questions posed above relate to the challenges of assessing effectiveness (in terms of health outcomes) and efficiency (in terms of costs) when re-allocating scarce resources in the health care sector, both in the United States and internationally.