The article discusses the methodology and the preliminary results of the research project entitled “Latvian language in Monolingual and Bilingual Acquisition: tools, theories and applications” (LAMBA). The project involves 25 researchers – linguists, educators, psychologists – from five institutions in Latvia and Norway, and focuses on phonological, lexical and morphosyntactic acquisition of Latvian as a native language in monolingual and bilingual settings. One of the main goals of the project is to develop a set of norm-referenced language assessment tools that would allow for accurate and time-efficient evaluation of language development in pre-school children.The article will focus specifically on the Latvian adaptation of MacArthur-Bates Communicative Development Inventories – a parental report tool that assesses the development of receptive and productive vocabulary, and certain aspects of grammar. Two CDI forms were adapted in the project: CDI Words and Gestures designed for use with children between 8 and 16 months of age, and CDI Words and Sentences designed for 16- to 36-month old children. Each CDI form contains extensive and language-specific checklists of lexical items, communicative gestures and grammatical constructions.