A patient problem list is a catalog of all health issues affecting a patient. Problem lists in electronic health records (EHRs) can play important roles for patient care and help identify target populations for quality improvement interventions or research studies. However, to serve these purposes, the problem list must be accurate and complete. This international study examined 10 health care organizations that use different EHRs in the United States, United Kingdom, and Argentina. Using the test case example of a diabetes diagnosis for any patient that had a recorded hemoglobin A1c value of greater than 7% (a test result that is diagnostic for diabetes), problem list completeness was found to range from 60% to 99% across the 10 sites. The authors conducted interviews with informatics leaders at the four top performing sites to determine factors that may contribute to higher success rates. Some practices that were common among the top performers were financial incentives, problem-oriented charting, gap reporting, shared responsibility, and links to billing codes. A prior AHRQ WebM&M commentary illustrates a patient care issue that arose due to an inaccurately recorded problem list.