Agreement of adjectives and participles and coordination of verbs in Russian as in many other morphologically rich languages is executed by inflectional endings. This paper presents Russian agreement types from the point of view of the similarity of nominal and adjectival endings. Three types of agreement are distinguished: the tautological, the reduplicative and the contrastive one. The analysis of Russian children’s spontaneous speech shows that the phonological similarity of nominal and adjectival inflectional endings may serve as a bootstrapping mechanism in the acquisition of agreement and coordination. This process is influenced by the frequency of the agreement type and by the order of the participants of NP. Consequences for the methodology of teaching Russian to foreigners are preposed.