A study of the relationships among infants' and toddlers' cognitive, expressive, and auditory communication scores and score change over 8 months and both extra-textual talk and emotional qualities of parent behavior during shared book reading and a study of the statistical interactions between emotional quality, extra-textual talk, and differences observed in families speaking English and Spanish based on data from 81 parents and their children in home-based Early Head Start programs in rural counties in the Midwest