The paper considers the problem of assessment in terms of its formative and summative functions, clarifies the definitions of the concepts of “formative” and “summative” assessment, gives a brief digression into the history of the issue, considers the role of formative assessment in the context of distance learning, in general, and in relation to professionally-oriented teaching of foreign languages, in particular. Special emphasis is placed on the revision of the assessment model in connection with the introduction of a new version of the Federal State Educational Standard, the use of formative assessment is illustrated by the example formative assessment of critical thinking skills in distance teaching how to read professionally-oriented texts in foreign languages. A model of descriptors for assessment of critical thinking skills in reading has been developed. Conclusions are made about the effectiveness of formative assessment for the development of the reader's personality in the framework of distance learning.