This paper examines opera drama in Mozart’s oeuvre. The individuality of Mozart’s style; the “poly-generic” quality of his works for the stage; and the presence of devices to portray characters common to different types of opera (buffa, singspiel); make it possible to talk about the composer creating a special genre of opera. This paper proposes to define this as “Mozartian drama.” It considers the genre of dramma giocoso (playful drama) to be its dramaturgical basis. The paper analyses the musical and dramatic material of the opera “Cosi fan tutte,” considering its composition and features of its musical language, and comes to a conclusion about the composer’s new understanding of its genre. In the course of the research, the author notes that Mozart transformed traditional operatic features. He establishes a special type of relationship between the performative and lyrical-psychological spheres of the operatic text and thereby generates a number of dramatic and compositional innovations. Comparing “Cosi fan tutte” to Mozart’s stage works of the 80-90s, the article also outlines the formation of the basic principles of “Mozartian drama.”