Research into the effects of residency work hour restrictions on patient safety has yielded mixed results in the surgical, medical, and intensive care settings. This retrospective analysis of patients admitted with an acute coronary syndrome—both before and after work hour restrictions had gone into effect—demonstrated improvements in the quality and efficiency of care with no adverse impact on patient outcomes. While the authors point out that a concurrent quality improvement program was also implemented during the study period, they call for greater research into the structural and process factors that may contribute to improved outcomes.