Theories of the acquisition of word meaning among children are reviewed and a case study of one child is reported. Three models of how the young child associates words with underlying concepts and conventional meanings are noted. While one model proposes that children initially overextend word meanings, the other two models propose that new words may initially refer only to a single referent. A monolingual Hebrew speaking child was studied over an 8-month period extending from the emergence of her first meaningful word to the time she combined words. Notes, recordings, and videotapes of interactions were used to collect data. The use of the 337 words acquired by the subject during the study period was analyzed according to extension categories, including underextension, regular extension, overextension, and unclassifiable. Definitions and examples of each category are provided. Underextension of word meaning during the early stages of acquisition was prevalent, but overall it was observed that different words follow different routes of meaning development. (RW)