Background Given an unacceptably high incidence of diagnostic errors, we sought to identify the key competencies that should be considered for inclusion in health professions education programs to improve the quality and safety of diagnosis in clinical practice. Methods An interprofessional group reviewed existing competency expectations for multiple health professions, and conducted a search that explored quality, safety, and competency in diagnosis. An iterative series of group discussions and concept prioritization was used to derive a final set of competencies. Results Twelve competencies were identified: Six of these are individual competencies: The first four (#1-#4) focus on acquiring the key information needed for diagnosis and formulating an appropriate, prioritized differential diagnosis; individual competency #5 is taking advantage of second opinions, decision support, and checklists; and #6 is using reflection and critical thinking to improve diagnostic performance. Three competencies focus on teamwork: Involving the patient and family (#1) and all relevant health professionals (#2) in the diagnostic process; and (#3) ensuring safe transitions of care and handoffs, and "closing the loop" on test result communication. The final three competencies emphasize system-related aspects of care: (#1) Understanding how human-factor elements influence the diagnostic process; (#2) developing a supportive culture; and (#3) reporting and disclosing diagnostic errors that are recognized, and learning from both successful diagnosis and from diagnostic errors. Conclusions These newly defined competencies are relevant to all health professions education programs and should be incorporated into educational programs.