For expressive vocabulary, both duration and frequency of vocabulary-related association-level talk mattered. As stated earlier, one possible interpretation of this finding is that interactive reading benefits children’s expressive vocabulary through active verbal involvement because it increases attention to words and provides production practice via child responses. The combination of association-level talk and more opportunities to make connections between words and science and social studies concepts in our intervention may have been associated with greater gains in vocabulary. It is also possible that both the frequency and duration of association-level talk around targeted vocabulary may have provided children with more opportunities to reproduce words heard in the storybook narrative (Sénéchal, 1997).