Béla Bartók's Piano Sonata Sz.80 is known for its integration of modernist language with traditional elements. However, due to Bartók's radical style of writing, it remains challenging to precisely define the piece's motives, voice-leading, and structure, even though pianists who perform it may intuitively comprehend them. Therefore, this study aims to elucidate the Piano Sonata's motivic and tonal structure, genesis and development. First, this study demonstrates Bartók's use of linear motives and progressions to elucidate the Piano Sonata's large-scale structure and demonstrate its internal coherence. Second, by comparing the published score with the facsimile of the Budapest Manuscript, it is possible to shed light on the significance of the changes that Bartók made, facilitating a better understanding of his intentions. Lastly, this study suggests interpretive decisions based on the analysis and manuscripts, thus providing performers with a more thorough understanding of the piece.