The relations between home literacy environment and child language ability were examined for 323 4-year-olds attending Head Start and their mothers or primary caregivers. Overall frequency of shared picture book reading, age of onset of picture book reading, duration of shared picture book reading during one recent day, number of picture books in the home, frequency of child's requests to engage in shared picture book reading, frequency of child's private play with books, frequency of shared trips to the library, frequency of caregiver's private reading, and caregiver's enjoyment of private reading constituted the literacy environment, and were measured using a questionnaire completed by each child's primary caregiver. Using a primary subsample of 236 children, a composite literacy environment score was derived from the literacy environment measures and was correlated with a composite child language measure, derived from two standardized tests of language skills. Depending on the form of regression analysis employed and depending on whether primary caregiver IQ and education were entered into the prediction equations, from 12% to 18.5% of the variance in child language scores was accounted for by home literacy environment. These analyses were cross-validated on a secondary subsample of 87 children with similar results. The strength of the relations between home literacy environment and child language are stronger in this study than in previous research, due to the use of statistically derived aggregate measures of literacy environment. The presence of substantial variability in home literacy environments in low-income families, and the substantial relations between these environments and child language outcomes has important implications for intervention.