A process akin to Schoenberg's "musical idea" accounts to a large degree for motivic coherence in the first movement of Beethoven's Piano Sonata Op. 10, No. 1. My article illustrates this process by means of a synthesis of Schenker's and Schoenberg's approaches to analysis. I use Schenkerian analysis to identify potential motives at various levels of musical structure, then interpret the treatment of some of these segments according to Schoenberg's model. I also show how the primary motivic process interacts with other such processes in the first movement.