The Receptive–Expressive Emergent Language Test–Fourth Edition (REEL-4) was designed to help you identify infants and toddlers who have language impairments or who have other disabilities that affect language development. It is especially useful as an assessment and planning instrument in Early Childhood Intervention programs mandated under P.L. 99-457. The REEL-4 has two subtests that make up the Language Ability composite, Receptive Language and Expressive Language, as well as a supplementary Vocabulary Inventory test, composed of the Nouns and Expanded subtests. Results are obtained from a caregiver interview. The REEL-4 is based on a contemporary linguistic model. It includes current studies related to normative base, reliability, and validity. The normative sample includes 1,019 infants and toddlers from around the nation. The demographic characteristics of the sample were matched to U.S. child population for the year 2019 reported in ProQuest Statistical Abstract of the United States 2018. The normative sample was stratified to on the basis of gender, race, Hispanic status, and geographic region. Standard scores, percentile ranks, and age equivalents are provided. (author abstract)