This document represents the first collaboration between two organizations, American Society of Parenteral and Enteral Nutrition and the Society of Critical Care Medicine, to describe best practices in nutrition therapy in critically ill children. The target of these guidelines is intended to be the pediatric (> 1 mo and < 18 yr) critically ill patient expected to require a length of stay greater than 2 or 3 days in a PICU admitting medical, surgical, and cardiac patients. In total, 2,032 citations were scanned for relevance. The PubMed/Medline search resulted in 960 citations for clinical trials and 925 citations for cohort studies. The EMBASE search for clinical trials culled 1,661 citations. In total, the search for clinical trials yielded 1,107 citations, whereas the cohort search yielded 925. After careful review, 16 randomized controlled trials and 37 cohort studies appeared to answer one of the eight preidentified question groups for this guideline. We used the Grading of Recommendations, Assessment, Development and Evaluation criteria to adjust the evidence grade based on assessment of the quality of study design and execution. These guidelines are not intended for neonates or adult patients. The guidelines reiterate the importance of nutritional assessment, particularly the detection of malnourished patients who are most vulnerable and therefore potentially may benefit from timely intervention. There is a need for renewed focus on accurate estimation of energy needs and attention to optimizing protein intake. Indirect calorimetry, where feasible, and cautious use of estimating equations and increased surveillance for unintended caloric underfeeding and overfeeding are recommended. Optimal protein intake and its correlation with clinical outcomes are areas of great interest. The optimal route and timing of nutrient delivery is an area of intense debate and investigations. Enteral nutrition remains the preferred route for nutrient delivery. Several strategies to optimize enteral nutrition during critical illness have emerged. The role of supplemental parenteral nutrition has been highlighted, and a delayed approach appears to be beneficial. Immunonutrition cannot be currently recommended. Overall, the pediatric critical care population is heterogeneous, and a nuanced approach to individualizing nutrition support with the aim of improving clinical outcomes is necessary.