In Medical Care, Ann Kutney-Lee, Linda Aiken and colleagues analyze patient and nurse outcomes in Magnet and non-Magnet hospitals in order to establish whether there is a causal link between Magnet designation and improved outcomes. Magnet hospitals are accredited by the American Nurses Credentialing Center for excellence in nursing. The authors analyzed retrospective data for a sample of hospitals in Pennsylvania that attained Magnet recognition between 1999 and 2007 and compared it to hospitals that remained non-Magnet. The outcome measures were surgical 30-day deaths, failure-to-rescues, nurse-reported quality measures and nurse outcomes. The study finds a significant reduction in mortality and failure-to-rescues in Magnet hospitals over time compared to non-Magnets. In addition, it also shows improvements in nurse-reported quality of care and nurse outcomes in Magnet hospitals. As one of the first longitudinal studies of Magnet hospitals, these findings provide early evidence for a potential causal link between the improvement of nurse work environments and patient outcomes.