The Paediatric Index of Mortality (PIM) was revised to reflect improvements in pediatric intensive care outcomes. This international, multi-center, prospective, observational study involved 12 specialist pediatric intensive care units and two combined adult-pediatric units in Australia, New Zealand, and the United Kingdom. The study included 20,787 patient admissions of children under 16 years old, after excluding 220 transferred patients and one still-in-ICU patient. A revised model, PIM2, was developed using forward and backward logistic regression, incorporating three variables derived from the main reason for ICU admission. The model was tested on data from seven units and showed good fit and discrimination (deciles of risk goodness-of-fit χ² 8.14, p=0.42; area under the ROC plot 0.90 [0.89–0.92]). The final PIM2 model, derived from 19,638 survivors and 1,104 deceased children, also performed well (χ² 11.56, p=0.17; area 0.90 [0.89–0.91]). PIM2 is suitable for continuous monitoring of pediatric intensive care quality, providing mortality risk estimates based on data available at ICU admission.The Paediatric Index of Mortality (PIM) was revised to reflect improvements in pediatric intensive care outcomes. This international, multi-center, prospective, observational study involved 12 specialist pediatric intensive care units and two combined adult-pediatric units in Australia, New Zealand, and the United Kingdom. The study included 20,787 patient admissions of children under 16 years old, after excluding 220 transferred patients and one still-in-ICU patient. A revised model, PIM2, was developed using forward and backward logistic regression, incorporating three variables derived from the main reason for ICU admission. The model was tested on data from seven units and showed good fit and discrimination (deciles of risk goodness-of-fit χ² 8.14, p=0.42; area under the ROC plot 0.90 [0.89–0.92]). The final PIM2 model, derived from 19,638 survivors and 1,104 deceased children, also performed well (χ² 11.56, p=0.17; area 0.90 [0.89–0.91]). PIM2 is suitable for continuous monitoring of pediatric intensive care quality, providing mortality risk estimates based on data available at ICU admission.