Background: Recent reports, including the Institute of Medicine’s Improving Diagnosis in Health Care, highlight the pervasiveness and underappreciated harm of diagnostic error, and recommend enhancing health care professional education in diagnostic reasoning. However, little is known about clinical reasoning curricula at US medical schools. Objective: To describe clinical reasoning curricula at US medical schools and to determine the attitudes of internal medicine clerkship directors toward teaching of clinical reasoning. Design: Cross-sectional multicenter study. Participants: US institutional members of the Clerkship Directors in Internal Medicine (CDIM). Main Measures: Examined responses to a survey that was emailed in May 2015 to CDIM institutional representatives, who reported on their medical school’s clinical reasoning curriculum. Key Results: The response rate was 74% (91/123). Most respondents reported that a structured curriculum in clinical reasoning should be taught in all phases of medical education, including the preclinical years (64/85; 75%), clinical clerkships (76/87; 87%), and the fourth year (75/88; 85%), and that more curricular time should be devoted to the topic. Respondents indicated that most students enter the clerkship with only poor (25/85; 29%) to fair (47/85; 55%) knowledge of key clinical reasoning concepts. Most institutions (52/91; 57%) surveyed lacked sessions dedicated to these topics. Lack of curricular time (59/67, 88%) and faculty expertise in teaching these concepts (53/76, 69%) were identified as barriers. Conclusions: Internal medicine clerkship directors believe that clinical reasoning should be taught throughout the 4 years of medical school, with the greatest emphasis in the clinical years. However, only a minority reported having teaching sessions devoted to clinical reasoning, citing a lack of curricular time and faculty expertise as the largest barriers. Our findings suggest that additional institutional and national resources should be dedicated to developing clinical reasoning curricula to improve diagnostic accuracy and reduce diagnostic error.