The ability of young children to communicate at the time they produce their first words was studied, with particular reference to the question of whether children are able to modify their requests depending on the adult's response. The subjects were four children ranging in age from 15 to 18 months; the data were their requests of adults coded from videotape recordings of each subject at free play with the experimenter and the mother when she desired. The sessions took place over a period of eight months. An analysis of the requests made of adults by the subjects revealed sequences of requests in which each request had the same goal. Two predictions were made: (1) change was expected more often when an initial request met with failure than when one met with success; and (2) any changes occurring in sequences involving success were expected to be reductions in behaviors used to make the request initially whereas changes in sequences involving failure would be more likely to be additions and/or substitutions of new behaviors. These predictions were confirmed. Data suggesting that the differences in the kind of changes made reflected knowledge of listener needs proved difficult to interpret and point the way to further research. (AMH)