As more than 40 states face present and projected deficits in their health care budgets, some legislatures are considering market-based reforms to control rising health care costs. This continues a trend begun in the 1990s that emphasized market competition over state regulation and mandates. However, little is known about the impact of many market-based reforms on quality of care. This Issue Brief evaluates the effect of one reform—the deregulation of hospital reimbursement rates in New Jersey—on one important outcome of care—mortality from acute myocardial infarction (heart attack). The findings serve as a reminder that cost-constraining reforms may reduce the quality of care, particularly for uninsured and other vulnerable populations.