This monograph deals with the emergence, semantic peculiarities, and development of the phraseological system of the Russian language in the 18th century. Based on extensive phraseological material, a model for the diachronic analysis of phraseological units is developed, which allows for the examination of historical phraseology at different levels. The focus of the book is on phrase-forming processes, subject areas, foreign language elements, and semantic fields in 18th-century Russian phraseology. Additional focal points include the archaisation and decline of phraseological units, changes in their structural-semantic organization, as well as their evolution in terms of variation and polysemy.