This study investigated whether mothers' responses to their infants' gestures play a role in their infants' vocabulary development. Eight infants were observed interacting at home with their mothers on 2 occasions, when the infants were 10 to 12 months old, and 16 to 18 months old. Videotapes of the observations were transcribed and coded for maternal utterances, infants' gestures, infants' other actions, and infants' verbal production. Data pertaining to the relation between maternal references to objects and actions in response to 10- to 12-month-old infants, and 16- to 18-month-old infants' vocabulary were analyzed. Results indicated that the frequency with which mothers named the objects on which 10- to 12-month-old infants focused was correlated with 16- to 18-month-old infants' total number of words used. The ratio of instances of maternal naming of objects in response to 10- to 12-month-old infants' gestures and instances in response to infants' other actions was correlated with the number of types of words 16- to 18-month-old infants used and the percentage of nouns in the infants' vocabularies. A list of 17 references is provided. (Author/SM)