Noting the scientifically substantiated link between children's early family experience and their later intellectual growth, this book describes a longitudinal study of the circumstances of early language learning and the central role of home and family in the emergence of language and word learning. The vocabularies of 42 children were studied from the time they first began to say words at about 1 year until they were about 3 years old. The study also observed the children's interactions with other persons in their families which formed the contexts for their word learning. Results indicated that the most important factors to language acquisition are the economic advantages of children's homes and the frequency of language experiences. The basic findings from the study are that children who were born into homes with fewer economic resources learn fewer words, have fewer experiences with words in interactions with other persons, and acquire a vocabulary of words more slowly. Five parenting features that predicted future achievement were: (1) language diversity; (2) feedback; (3) guidance style; (4) language emphasis; and (5) responsiveness. The book concludes by outlining an agenda for intervention that would begin in the home and very early in a young child's life, with a focus on the social influences on language and its acquisition within the cultural context of the family. Two appendices contain a table of quality features of parent language and interaction, and 20 figures of data. Contains 88 references. (AP)