Comparative analysis of substantive adjectives with the suffixes -at-, -ast-, -ist-, all having a common additional component of intensity in their derivational semantics, was performed. The adjectives were considered within a series of derivational means used to express the semantic category of intensity. The study is relevant due to the necessity to create a fundamentally new and cognitively oriented description of word-formation units of the Russian language from the standpoint of the systemic functional approach. The purpose of the study was to establish the systemic and categorical status of substantive suffixal adjectives with the semantics of intensity, as well as their functional correlations. Conclusions were made about the subcategorizing character of this meaning in the field of mutational semantics of Russian adjectives (the systemic status of its carriers is a derivational subtype with the suffix -ast- and word-formation subtypes with the suffixes -at-, -ist-). Functional features of the derivatives with each suffix were defined. Similarities and differences between them were revealed. Their systemic and functional relationship (synonymy and parallelism) was established. Zones of functional dominance were found.