Children entering institutional education can activate the linguistic and non-linguistic norms they bring from home. These norms, however, are very diverse in their nature and children from the same age-group remain at different levels in terms of language-acquisition. In our paper we seek to identify where and what sort of problems may arise in acquiring the mother-tongue, what factors may hinder the acquisition of the first language, what are the symptoms of backwardness in the field of linguistic–communication and which areas measuring tests tend to focus upon. Finally by presenting an indication system we would like to show what opportunities observation may have in purposeful development.Keywords: native language acquisition, linguistic competence, measurementof communication skills, observation of children’s language performance.