Vocabulary Size in the First Language

<jats:title>Abstract</jats:title> <jats:p>English‐speaking adults may know and use as many as 150,000 different words. How do children begin the task of learning words and what factors influence the size and diversity of vocabulary development throughout the lifespan? This entry explores the beginnings of word‐learning, traces its developmental trajectory from infancy to adulthood, and examines factors related to the size and scope of the lexicon.</jats:p>