The present study aimed: (1) to systematically describe and classify the speech input received by children of specified ages from their mothers in the home, (2) to investigate the interdependence between the quality of the mother's speech, her socio-cultural background, and her children's level of intelligence, and (3) to determine whether some attributes of the mother's speech can be modified if she wishes. The speech of 57 mothers from two ethno-cultural groups was recorded during two 60-minute sessions in each home. Siblings of two ages were observed: a child not yet talking (about 1 year old), and a child already talking (about 3 years old). A third visit yielded background information from the mother, and during a fourth visit (1 year later), the older child and the mother were given intelligence tests. The units of speech analyses were words and sentences, dealing with speech aspects of amount, content, and form. Although all variable factors affecting verbal behavior were not controlled, study results yielded (1) meaningful measurement of four aspects of speech, and establishment of preliminary norms to evaluate a mother's manner of speech, (2) significant correlations of the children's intelligence level with the measures of mothers' speech, and (3) preliminary indications that readiness and ability of the mother to modify her speech is correlated with her intellectual level (part of an ongoing experiment). Appendixes are included. (Author/NH)