Computerized provider order entry (CPOE) systems have been widely implemented to prevent adverse drug events due to prescribing errors. This direct observation and interview study in an outpatient pharmacy setting describes changes in practice as a result of electronic prescribing. Consistent with prior studies investigating unintended consequences of CPOE, researchers identified new errors associated with electronic prescribing, as well as potential methods to reduce adverse drug events. To improve safety, the authors recommend developing systems to track abandoned prescriptions, offering incentives for pharmacies to utilize electronic prescribing, and enhancing the interface between electronic health record and pharmacy computer systems to decrease manual entry, limit duplicated prescriptions, and expedite clarification requests. A past AHRQ WebM&M commentary describes how a nurse entered an outpatient prescription for the wrong patient and deleted it, mistakenly assuming it would cancel the order.