The essay begins with the overview of Russian-Soviet piano music from the second half of the 19th century to the end of the 20th century. Then, biographical information about Sergei Slonimsky and an overview of his major compositions is provided. The majority of the paper focuses on Slonimsky's Sonata for Piano (1963). A brief discussion of the Sonata's compositional history is followed by the formal analysis of the overall structure of the work. Slonimsky's original principle of organization of the music is emphasized: the system of constant interrelation of the main thematic material combined with elements of the sonata-allegro form. In the analysis of the harmonic language of the piece, the composer's extensive use of Russian folk elements such as diatonic melodies, sigh motives, parallel triads, and simultaneous use of the lower third with the major triad is pointed out. The rest of the paper focuses on issues of interpretation and performance. Special notice is given to the problem of incorporating a percussive type of playing with the elements of folk cantilena singing. The paper concludes with the history of Sonata's performances and a discussion of current recordings.