Drawing on survey and interview evidence, this chapter explores the effect of coverage denials on patients’ health and economic security. Most Americans report an inability to pay an unexpected $1,000 bill, so, with notably expensive health care, denials can be devastating. Too often, when coverage is denied, patients abandon their treatments, a dynamic shown not only through physician surveys, but also through original survey evidence of patients, half of whom reported delaying or abandoning their prescribed care. Further, the people most likely to do so are typically Black or Hispanic or less affluent, and nearly half of patient respondents reported that their health condition declined. In fact, some patients may not survive at all. Marginalized patients are also more likely to postpone non-medical purchasing to accommodate unexpected health insurance barriers, suggesting the far-reaching consequences of prior authorization. The evidence shows not only that tools of managed care produce frequent coverage denials, but also that this practice shifts risk from insurers to patients, yielding new health and economic insecurities, especially for patients from marginalized backgrounds.