Missed or delayed diagnoses lead to delays in care and significant preventable harm for patients. Despite an increasing focus on diagnostic error, accurate measurement and implementation of effective strategies for mitigating its adverse effects remain challenging. The Gordon and Betty Moore Foundation recently announced a new $85 million initiative focused on diagnostic excellence that takes into account health care costs, timeliness, and individual patient needs. This initiative will focus on three clinical areas including cancer, infections, and cardiovascular events. Through this funding, the foundation hopes to stimulate novel approaches to measuring diagnostic performance and plans to assess the effectiveness of new technologies in improving the diagnostic process. A PSNet perspective highlighted ongoing challenges related to diagnostic error.