There is a great deal of public awareness regarding the shortage of nurses in U.S. hospitals and the consequent threat to patient safety, and growing evidence suggests that understaffing affects quality of care. However, little is known about whether the educational composition of registered nurses (RNs) in hospitals is related to patient outcomes, even as the numbers of nurses with bachelor's degrees (BSNs) has grown substantially. This study tested whether hospitals with higher proportions of direct-care RNs with BSNs or higher degrees have lower risk-adjusted mortality rates and lower rates of deaths among patients with serious complications. Data was drawn from discharge abstracts from 232,342 patients aged 20 to 85 years at 168 Pennsylvania acute-care hospitals; and surveys completed by 10,184 hospital nurses. Descriptive statistics and logistic regression models were used to analyze the data. Findings showed that the odds of mortality and failure to rescue was 19 percent lower in hospitals where 60 percent of the nurses had BSNs or higher degrees than in hospitals where only 20 percent of nurses did. Analysis limitations include the potential for response bias in educational and staffing measures given the 52 percent response rate; future studies also would benefit from longitudinal datasets from more than one state. This study's documentation of significantly better patient outcomes in hospitals with more highly educated RNs underscores the importance of placing greater emphasis in national nurse workforce planning on policies to alter the education composition of the future nurse workforce. Open access journal article.