The article is dedicated to the release of the third edition of “Russkii yazyk” encyclopaedia (Moscow, 2020) which continues and promotes the tradition of providing the main data about the Russian language. The article presents not only the announcement of the new edition (nonetheless giving the detailed information about it), but also an account of the over-40-yearlong history of the “Russkii yazyk” encyclopaedia. It highlights the features uniting all three of its editions and the distinct points each of them has. The article demonstrates that many principles of presenting information on the language and Russian studies, the terms making up the glossary as well as the illustrations for the articles were created back in the fi rst edition (1979) and remained ever since. However, each of the three editions had a number of particular changes both in content and in the layout. While the fi rst edition was a small book, the second one was a substantial volume printed in a larger font and supplemented with many colourful illustrations, maps and tables. In the second edition, the number of entries on historicalcultural and source-study issues increased and new topics were covered, but personalia articles devoted to the linguists were excluded. The third edition of the encyclopaedia is even larger than the previous ones. It is certainly the main focus of the article. The book has changed and expanded; the majority of its entries were revised or written anew. The authors use the example of the “Tainye yazyki” [Secret languages] entry present in all three editions to demonstrate the revisions, additions and elaborations introduced in every new version. The appearance of the new edition of the “Russkii yazyk” encyclopaedia became a milestone in the development of Russian studies: the book summarises the existing research and records the obtained results as well as opening up prospects to the researchers, setting new goals and offering new avenues for development.