The original pediatric complex chronic conditions (CCC) classification system developed in 2000/2001 is the gold standard in classifying children with life-limiting illnesses. It was significantly modified in 2014; yet the two systems have not been evaluated. The objective of this study was to evaluate the agreement and validity of the original versus the modified CCC classification systems. Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID) data from 2012 was used with a sample of infant decedents less than 1 years. The agreement (i.e., Cohen's Kappa Statistic) and validity (i.e., sensitivity, specificity, and positive predictive value [PPV]) statistics were calculated. Among the 10,175 infants that were classified, the modified system performed well in identifying infants who had a CCC, and it captured infants that the original classification did not. The modified system represents an improvement over the original, but additional testing is warranted. [ABSTRACT FROM AUTHOR]