The National Academy of Medicine (formerly the Institute of Medicine) launched the patient safety movement with the publication of its report To Err Is Human. The group has now released a report about diagnosis, which they describe as a blind spot in health care. Available evidence suggests that most Americans will experience a missed or delayed diagnosis in their lifetime. The committee made several recommendations to improve diagnosis, including promoting teamwork among interdisciplinary health care teams, enhancing patient engagement in the diagnostic process, implementing large-scale error reporting systems with feedback and corrective action, and improving health information technology (as recommended in prior reports). Longer-term recommendations include establishing a work system and safety culture that foster timely and accurate diagnosis, improving the medical liability system to foster learning from missed or delayed diagnoses, reforming the payment system to support better diagnosis, and increasing funding for research in diagnostic safety. The report emphasizes the need for much more effort, and far more resources, at the practice, policy, and research levels to address this pressing safety problem.