Researchers find significant declines in both hospitalizations and ED visits among the population of AHCCCS beneficiaries enrolled under the Proposition 204 criteria as of June 30, 2011. Not surprisingly, these declines were the driven by those who became disenrolled during the freeze period, and especially by those who were never observed to reenroll in Medicaid at any point during the study period. These patterns point to a strong association between health insurance and the utilization of hospital-based care. They also strongly suggest that emergency departments do not function as a substitute for hospital admissions in the face of limited access to health insurance. With respect to the impact of re-acquired coverage on these behaviors, we find that while utilization does increase, the uptick (in terms of rates) is much smaller than the declines that preceded it.