In this article, we report the results of a large-scale population study based on the Latvian adaptation of Communicative Development Inventories (CDI) – a parental report tool aimed at mapping the lexical and grammatical development of children under the age of three. Two CDI forms are discussed: CDI I: ‘Words and Gestures’ (8–16 months), and CDI II: ‘Words and Sentences’ (17–36 months). This article ...