In our systematic review, we evaluated 15 instruments for their psychometric properties and clinical utility. Based on this review we recommend the COMFORT scale (Ambuel et al., 1992) for assessing postoperative pain and nonprocedural pain in mechanically ventilated pediatric patients. The Modified FLACC (Johansson & Kokinsky, 2009) and the MAPS (Ramelet et al., 2007) are recommended for assessing procedural pain and other brief painful events in mechanically ventilated pediatric patients (Dorfman et al., 2014).