Among Mozart's numerous individual keyboard works, the fantasias, K.394, K. 396, K. 397, and K. 475 comprise the freer forms of composition written for the keyboard. The keyboard fantasias of Mozart preserve in written-out forms the incredible power of improvisation in which the composer displayed his innermost expressiveness and his utmost delight at the keyboard. As an eminent keyboard player and great improviser Mozart was immensely successful in his fantasias in uniting the variety of sentiments and fanciful keyboard techniques that the eighteenth-century audience so favored. Thus, this study examines the stylistic traits contained in Mozart's keyboard fantasias: the idiomatic keyboard figurations, the expressive idioms, and the overall formal structures. It is evident that Mozart's fantasias show much influence of C. P. E. Bach's free fantasias in their adoption of improvisational procedures and expressive languages of the empfindsamer Stil. Nevertheless, in the fantasias, there are many other characteristic features that are uniquely Mozart's: his language of style galant, his talent for dramatic power, and his predilection, as a Classical master, for the clarity of formal structures. Mozart's keyboard fantasias, especially K. 397 and K. 475, are unique and original creations in which the subjective force of expression is welded into the objective logic of formal beauty; in these small spheres of fantasias Mozart brings rich diversity of musical resources into a unified whole. In short, Mozart's keyboard fantasias exemplify a perfect union of expressive content and structural balance suited to the eighteenth-century ideal of Classicism.