A concept set comprises a group of codes used to define a specific study variable, phenotype, or cohort. Each code set within the collection is linked to its corresponding variable definition, as applicable. The individual codes within these sets represent standard, authorized concept terms sourced from reputable ontologies like SNOMED, ICD, HCPCS, or CMS. The PEDSnet Data Coordinating Center curates code sets for specific studies and offers them for reuse in PEDSpace. Below, PEDSnet code sets are categorized by data domain for easy reference.