Failure to follow up on test results is a common source of missed or delayed diagnoses, especially in the outpatient setting. Even in systems with highly-integrated electronic health records, such as the Veterans Affairs health system, problems with test follow-up persist. This study explored various sociotechnical factors that may contribute to missed test results. Although the vast majority of facilities required that unread alerts remain in the ordering providers' inbox for at least 14 days, only about 70% of facilities had some mechanism to prevent alerts from remaining unread. Interviews with patient safety managers and information technologists revealed a number of generalizable high-risk scenarios. Tests ordered by trainees frequently led to issues with follow-up since trainees often rotated to other sites and rarely followed full protocols to ensure test follow-up. Even when a surrogate was assigned to receive alerts during a clinician's absence, there were many problems with lack of clear responsibilities and communication. A previous AHRQ WebM&M commentary discussed the many issues that contribute to missed test follow-up.