This is a collection of the most valuable works of Solomon Katsnel"son (1907-1985), one of the leaders of Russian linguistics. His area of study was theory, methodology and history of linguistic forms and grammatical categories, and their relationship to thinking. In different periods of his life, Katsnel"son worked upon issues of psycholinguistics, child speech, comparative analysis of Indo-European and Germanic languages. In addition to his published works, this collection also includes chapters from his unfinished monographs as well as articles, essays, and works in progress. List of Katsnel"son"s publications and name index.