Abstract
From observer records, a count was made for each child, in a group of disadvantaged children in an experimental preschool, of usage and acquisition of descriptive adjectives, with and without noun referents. Procedures were sought which would effectively modify the low rates of adjective-noun combinations in the everyday language of all the children. Time in school, intermittent teacher praise, and social and intellectual stimulation were not effective in changing the low rates of using adjectives of size and shape. Group teaching effectively increased rates of using color- and number-noun combinations in the group-teaching situation, but was ineffective in changing rates of usage in the children's "spontaneous" vocabularies. By operating directly on the children's language in the free-play situation, making access to preschool materials contingent upon use of a color-noun combination, significant increases in such usage were effected in the spontaneous vocabularies of all the children. Preschool materials apparently functioned as powerful reinforcers. Though traditional teaching procedures were effective in generating adjective-noun combinations in that restricted situation, it was only through application of environmental contingencies that color names as descriptive adjectives were effectively and durably established in all the children's spontaneous vocabularies.