BACKGROUND: Emergence delirium (ED) frequently occurs in young children awakening from general anesthesia (GA). To date, research is limited by scales that are unable to discriminate the condition from other forms of agitation. AIM: The primary aim of this study was to determine the core behaviors of ED that discriminate the condition from pain and tantrum in young children and to cluster these behaviors according to the DSM-IV/V core diagnostic criteria and associated behaviors of delirium. METHOD: Children aged 18 months to 6 years (n=198) were observed upon awakening from GA following surgical or nonsurgical procedures to determine which behaviors categorize ED. Behaviors were recorded via a structured behavioral observation. Clinical opinion was sought to determine whether the child presented ED, pain, or tantrum. RESULTS: A chi-square analysis revealed children with ED were significantly more likely to display activity, nonpurposefulness, eyes averted, stared or closed, no language, and nonresponsivity. These behaviors were not significantly associated with pain or tantrum. A logistic regression showed eyes averted or stared and nonpurposefulness were significant predictors of ED, while no language and activity were not significant predictors of ED. CONCLUSIONS: Children with ED are significantly more likely to display nonpurposefulness, eyes averted, stared or closed, and nonresponsivity. These behaviors were not significantly associated with pain or tantrum and are believed to reflect the DSM-IV/V diagnostic criteria for delirium. Associated behaviors of ED identified by this research are irrelevant language, activity, and vocalization.