This study examined the nature of the role of the violin in the sonatas of Wolfgang Amadeus Mozart. Special emphasis was placed on the evolving role of the violin as the researcher looked at a movement from an early sonata and a corresponding movement from a late sonata. In the early sonata, K. 304, the dynamic between the piano and the violin is not in sync. The violin part retains no independence, no separate identity from its piano counterpart. Removing the violin would still result in a complete thematic movement. The dynamic between the violin and piano changes as Mozart matures. In the sonata K. 526 the violin and piano are more equal partners. There is independence in the violin and the two instruments truly work together to create chamber music.