The paper discusses the problem of phase structure acquisition in Russian children. The study is based on 213 oral unprepared elicited narratives by Russian monolingual children at ages from 2 years and 7 months to 7 years and 6 months old. The findings show that discerning action phases depends on the development level of the child's cognitive abilities as well as on the type of the text: for example, unprepared narratives require the use of starting-phase verbs, continuing actions may be described with repeated verb forms, while concluding phases are usually omitted. My analysis shows that Russian-speaking children start using prototypical phase verbs as of the age of 4 years and 6 months, prior to which they tend to describe the starting phase of actions by using prefixed inchoative verbs. In the course of language mastering, the composition of starting-phase descriptions evolves in the following order: prefixation > phase verb stat ‘become' > phase verb nachat / nachinat ‘begin' > verbs poyti ‘go' and reshit / reshat ‘decide' (notably, the latter only acquire phase meanings at an age of 7 to 8 years). Thus, at early stages of language acquisition, phase meanings tend to be expressed by verbs' lexical meanings. The lack of evaluation connotations in the use of phase verbs in child speech and the poor repertoire of peripheral phase verbs prove that although Russian-speaking children generally master phase meanings by the age of 7 years and 6 months, one cannot describe this ability as developed in full.