Researchers have consistently found a link between the quality of early parent-child book-reading interactions and children's language skill. Two aspects of quality (level of abstraction and utterance function) were examined simultaneously in the current study to further refine our understanding of how parents' talk during shared reading predicts children's vocabulary growth and elicits children's participation in book reading. To achieve this aim, the authors examined mothers' extratextual utterances while reading to their preschool children across a continuum of four levels of abstraction (two literal and two inferential) and in terms of utterance function ("wh"- question, yes/no question, and statement). In a sample of 49 mother-child dyads (mean child age = 4.47 years), the authors found that mothers' inferential yes/no questions and statements predicted children's receptive vocabulary growth over six months, controlling for children's age, mothers' education, and frequency of reading, and that mothers' inferential "wh"- questions and literal utterances of all types were not predictive of children's vocabulary growth. Using sequential analysis, the authors also found significant contingencies between mothers' utterances and children's responses during shared reading that were within the same level of abstraction across all utterance functions. These results are discussed in relation to prior work that has largely examined these two qualities of parent-child book interactions separately.