Delirium is characterized by transient behavioral manifestations of acute brain disturbances. Delirium in the intensive care unit has been well researched and documented in the adult population. Pediatric delirium research has lagged, but recent developments in screening tools have shed light on the prevalence of delirium among children. The overall prevalence of delirium in the pediatric intensive care unit is 25%. A recent study showed a prevalence of 49% in the pediatric cardiac intensive care unit; this higher prevalence may be due to factors related to critical illness and the postoperative environment. This article is intended to increase awareness of delirium in the pediatric cardiac intensive care unit and give nurses the tools to identify it and intervene when necessary. A definition of delirium is provided, and its prevalence, risk factors, and current knowledge are reviewed. Available screening tools and environmental and pharmacological interventions are explored.