The investigation was designed to determine the effectiveness of day care intervention on the use of intentional communicative behaviors by 26 twenty month old low socioeconomic status infants at risk for developmental retardation, and to compare their communicative development to a group of 14 normally developing middle class infants. Literature was reviewed on the origin and etiology of the notion of "high risk" infants and on relevant variables as possible contributors to developmental delay. The review revealed that the age at which high risk infants begin to deviate from other infants is around 18 to 24 months, which coincides with the onset of the use of single words in language development. First, the total frequency with which the infant initiated a communicative act to the mother during a free play interaction situation was determined. Two different functions of communication were observed in two separate settings--first, a measure of the infant's use of the "showing" function of communications was obtained in a free play interaction with the mother and second, a measure of the infant's use of the "requesting" function of communications was obtained during an experimental communications task. Measures of the infants' social development were also obtained for three variables: the amount of time the dyad played or read together, the amount of time the mother read alone, and the frequency of the mother's attempts to modify the infant's behavior or activity. For the infants observed in the study, day care intervention did influence communicative behaviors. Results did not support the notion that there are cognitive prerequisites to language. In addition, an inconsistent relationship was found between the infants' performance on the subscales of the Uzgiris and Hunt Ordinal Scales as a measure of sensorimotor development and their performance on the measures of communications. The study did support the notion that environmental factors can positively affect the development of early communicative development. Additional study data are appended. (SBH)