The piano trio compositions of Haydn and Mozart have been only briefly addressed in musicological literature so far. This study focuses on the genre-specific works of these two classics and aims to illuminate the history of the genre before Haydn and Mozart, as well as to highlight selected examples that reveal trends relevant to both the later development of the genre and the composers' own contributions. Comparisons with lesser-known contemporaries are also included to place their work in a broader context. Developments within the composers' works are demonstrated, and the unique structural development of the piano trio is documented. The emancipation of the cello as a nearly equal chamber music partner is a development that begins with Haydn and is continued by Mozart.