This book highlights a transition from the study of language and cognition to that of language in cognition. It presents an integrative theory of cognitive development, emphasizing the important role that language plays in taking the two to five year old child to new levels of cognitive operations in memory, forming concepts, categories, processing narratives, and understanding other people's intentions. The author considers biological evolution the source of both language and culture, but she argues that qualitatively different modes of thinking and knowing emerge therefrom.