This paper studies the process of learning to write from an insider perspective, by adopting the framework of implicit theories of learning. We interviewed 160 children attending kindergarten or primary education in public schools in Argentina (20 children from each of the eight grades from kindergarten to seventh grade). Main questions explored children's accounts of their learning activity, learning difficulties and awareness of learning in the field of writing. The textual transcriptions of their oral responses were analysed with the lexicometric method. Results indicate an early shift from a direct theory of learning to write to an interpretative one revealing increasing complexity, dynamisation and internalisation of learning agency. (Contains 2 tables and 3 figures.)