Project Summary/Abstract One aspect of the mission of the NICHD is to support basic research in human development. The Language Development and Multilingualism program supports research into the mechanisms underlying typical language development and language related processes. The research proposed here will ask how children learn that a word has more than one meaning. Homophones are common in speech to and by children and yet most theories of word learning do not include an account of how they are learned. The proposed studies will use a cross- situational word learning task, where children learn new words for new objects without being specifically taught them, to directly test whether a range of previously posited information sources support children’s learning of homophones. These studies in particular ask how children learn about multiple meanings for words when they are not directly taught that a word has more than one meaning. Because this is how children learn most words, these studies will better represent real-world learning than other studies have. These studies support the mission of the NICHD by providing insight into processes of typical child development, specifically the learning of words. Understanding how children learn about homophones in speech may also have important implications for early literacy, as the need to map multiple meanings on to a single form also arises in the domain of reading.