Numerous problems for the performer of Mozart's Piano Concerto in C minor have been encountered through the examination of the manuscript autograph, editions, and recordings. Although the autograph and various editions have been studied before, this is the first discussion to include over sixty recordings of this concerto as well. Legibility of text and other editorial issues constitute one category of problems. Examples presented in Chapter 1 suggest that generally accepted readings of ambiguous passages found in different editions should not be considered as the only possible options for pianists. Shorthand methods and incomplete notation are discussed in Chapter 2. The fragments appearing sketchy and requiring or allowing for completion are examined. The particular cases of octave leaps (measures 142--45, 155--57, 159--63 of the third movement) and unreasonable interruption of sixteenth-note flow (first movement, measures 261--62 and 467--70) are presented in Chapters 3, 4, and 5 respectively, along with many ideas for elaboration in these places. Fermata embellishments are not discussed in this study; however, comprehensive lists of available cadenzas and Eingange are provided in Appendix A. Two original cadenzas to the first movement by this author are included in Appendix B.