This observational study sought to determine whether the ACGME 2011 duty hour reforms led to changes in 30-day mortality or readmissions for several medical diagnoses—acute myocardial infarction, stroke, acute gastrointestinal bleed, or congestive heart failure—and for general, orthopedic, or vascular surgery. The authors examined how hospital teaching status, which they defined using resident-to-bed ratio, affected outcomes for these conditions. This measure provides insight into the intensity of teaching at a given institution rather than defining each hospital as teaching versus nonteaching. During the study time period, although readmissions and mortality both declined overall, this decrease did not differ based on teaching status, suggesting that the improvement in readmissions and 30-day mortality is not attributable to duty hour reform. These results are consistent with prior work following the 2003 duty hour reforms which has failed to demonstrate benefit to patient outcomes from costly duty hour reforms. An editorial discussing this work and a companion study urge flexibility in duty hours for physicians in training.