This report summarizes the evidence and rationale supporting the components of the cste/cdc mis-c surveillance case definition and describes the methods used to develop the definition. these methods included convening mis-c clinical experts (i.e., consultants): regarding identification of MIS-C and its distinction from other pediatric conditions, a review of available literature comparing MIS-C phenotype with that of pediatric COVID-19 and other hyperinflammatory syndromes, and retrospective application of different criteria to data from MIS-C cases previously reported to CDC.