Abstract
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 discusses the Internet-based methodology used for the data collection, reports the main developmental trends of the lexical development of Latvian children, and compares these trends to analogous data from American English, Norwegian, and Russian.