Study objective: Ketamine is widely used in emergency departments (EDs) to facilitate painful procedures; however, existing descriptors of predictors of emesis and recovery agitation are derived from relatively small studies. Methods: We pooled individual-patient data from 32 ED studies and performed multiple logistic regression to determine which clinical variables would predict emesis and recovery agitation. The first phase of this study similarly identified predictors of airway and respiratory adverse events. Results: In 8,282 pediatric ketamine sedations, the overall incidence of emesis, any recovery agitation, and clinically important recovery agitation was 8.4%, 7.6%, and 1.4%, respectively. The most important independent predictors of emesis are unusually high intravenous (IV) dose (initial dose of ≥2.5 mg/kg or a total dose of ≥5.0 mg/kg), intramuscular (IM) route, and increasing age (peak at 12 years). Similar risk factors for any recovery agitation are low IM dose (<3.0 mg/kg) and unusually high IV dose, with no such important risk factors for clinically important recovery agitation. Conclusion: Early adolescence is the peak age for ketamine-associated emesis, and its rate is higher with IM administration and with unusually high IV doses. Recovery agitation is not age related to a clinically important degree. When we interpreted it in conjunction with the separate airway adverse event phase of this analysis, we found no apparent clinically important benefit or harm from coadministered anticholinergics and benzodiazepines and no increase in adverse events with either oropharyngeal procedures or the presence of substantial underlying illness. These and other results herein challenge many widely held views about ED ketamine administration.