She believes that language is the catalist of cognitive growth: it enables the child to process narratives, to form concepts and categories, to model the beliefs of other individuals.

Nelson is interested in how the child comes to participate in the social life of his community. She bridges Vygotsky's theory of the mediating language (language provides a semiotic mediation of knowledge) and Donald's model of coevolution of culture and mind (mind developed through four stages).
She applies Merlin Donald's phylogenetic model to the ontogenetic scale, and thus argues that the mind grows through a number of stages: the emergence of the historical self, the emergence of the narrative self, the emergence of the paradigmatic mind, the emergence of the temporal mind, the emergence of the projective mind. These stages mimick Donald's evolutionary phases, although not quite (in children the event, mimetic, narrative and symbolic stages overlap to some extent throughout development).
"Language is the medium through which the mind becomes culturally mediated", through which the shared meanings of society take over the child's mind.