The majority of individual errors are due to failure to perform automatic or reflexive actions. A major risk factor for these "slips" is being interrupted or distracted while performing a task. This review examined the literature on the incidence, risk factors, and effects of interruptions in several clinical settings, ranging from outpatient clinics to the operating room. Although distractions are common and may be associated with increased risk for error, particularly if they occur during medication administration or signout, the authors point out that many interruptions may be necessary to communicate urgent clinical information. They argue for complexity theory–based research to delineate the harmful and beneficial aspects of interruptions, rather than for interventions that seek to simply eliminate interruptions. Checklists have been widely adopted as a means of preventing errors of omission, which may be precipitated by interruptions.