The aim of this article is to describe the methods of presenting grammatical information used in the Dictionary of Everyday Russian Language of Muscovite Rus' of the 16th–17th Centuries. The dictionary represents the general Russian colloquial speech of the specified period, using only secular texts of various genres (excluding Church Slavonic texts). A distinctive feature of the dictionary is the principle of completeness, according to which both lexical and grammatical features of the material are described in the most detailed manner possible. For the first time, the article summarizes data from the published 10 volumes of the Dictionary (2004–2025), which present words and fixed combinations from A to K (over 12,000 dictionary entries). The grammatical marks of the Dictionary are described against the background of other lexicographic sources of the studied period, which represent different regional variants of Russian or the language of the broader area. All of them are explanatory, i.e., focused primarily on capturing the semantics. Grammatical description is usually given little attention. Common to all is the approach to selecting grammatical material: lexemes of all parts of speech, both notional and functional, are fixed. In contrast to other sources, grammatical information in the Dictionary can be presented at different levels of a word's semantic structure: not only for a lexeme but also for individual meanings and shades of meaning. All units receive a part-of-speech characterization. The system of grammatical marks for nouns and verbs is most thoroughly developed in the Dictionary. For nouns, all identified features of gender and number are indicated (e.g., feminine nouns can be used as male personal names and nicknames). For verbs, aspect and its peculiarities (e.g., mismatch of aspect for different word meanings), impersonality, as well as participles and gerunds, are designated. An important feature of the Dictionary is the reflection of grammatical characteristics related to word compatibility: types of verb government, the possibility of combining with a specific case for nouns, adjectives, adverbs, and prepositions are indicated. The categories of functional parts of speech are described. Grammatical transposition (change of part of speech) and grammatical characteristics of phraseological units are also described; neither of these is represented in other historical dictionaries of the Russian language. Thus, the grammar of words and fixed combinations receives an exhaustive description in the Dictionary. This allows to represent the complex, dynamic, and variable grammatical system in the early period of the national language formation.