Computerized provider order entry (CPOE) is one of the most widely recommended—and underutilized—safety strategies in health care. Prior research has argued that CPOE must be combined with decision support, ideally at the point of care, in order to effectively change clinician behavior. However, this meta-analysis of 32 trials of point-of-care computer reminders found only small overall improvements in adherence to target processes of care. A few trials reported much larger improvements, but the reasons for this are unclear, probably reflecting a combination of specific system and reminder design features, and perhaps cultural or contextual features of the institutions. Until further research identifies the specific design and contextual factors that reliably predict clinically worthwhile improvements in care, hospitals implementing CPOE may continue to find themselves conducting exercises in trial and error.