Objective Delirium is an increasingly recognized hospital complication associated with poorer outcomes in critically ill children. We aimed to evaluate risk factors for screening positive for delirium in children admitted to a pediatric cardiac intensive care unit (CICU) and to examine the association between duration of positive screening and in-hospital outcomes. Study design Retrospective cohort study in a single-center quaternary pediatric hospital CICU evaluating children admitted from March 2014-October 2016 and screened for delirium using the Cornell Assessment of Pediatric Delirium. Statistical analysis used multivariable logistic and linear regression. Results Among 942 patients with screening data (98% of all admissions), 67% of patients screened positive for delirium. On univariate analysis, screening positive was associated with younger age, single ventricle anatomy, duration of mechanical ventilation, continuous renal replacement therapy, extracorporeal life support, and surgical complexity, as well as higher average total daily doses of benzodiazepines, opioids, and dexmedetomidine. On multivariable analysis, screening positive for delirium was independently associated with age <2 years, duration of mechanical ventilation, and greater than the median daily doses of benzodiazepine and opioid. In addition to these factors, duration of screening positive was also independently associated with higher STAT category (3-5) or medical admission, organ failure, acute kidney injury (AKI), and higher dexmedetomidine exposure. Duration of positive delirium screening was associated with both increased CICU and hospital length of stay (each additional day of positive screening was associated with a 3% longer CICU stay [95% CI = 1%-6%] and 2% longer hospital stay [95% CI = 0%-4%]). Conclusions Screening positive for delirium is common in the pediatric CICU and is independently associated with prolonged intensive care unit (ICU) and hospital stay. Longer duration of mechanical ventilation and higher sedative doses are independent risk factors for screening positive for delirium. Efforts aimed at reducing these exposures may decrease the burden of delirium in this population.