This thesis proposes a methodology for understanding the form of a Baroque prelude, particularly the preludes to the Six Suites for Unaccompanied Violoncello written by Johann Sebastian Bach. Four musical dimensions, tonal structure, motive, texture, and the potential implications of a piece’s genre, parse the preludes in different ways. As the features of these musical dimensions undergo either an evolution or a dramatic change over the course of each prelude, they each suggest a different form. Points of change in each dimension delineate segments in the music. When aligned, these changes create significant formal junctures and suggest an overall form for the movement. Analysis of the interplay among the musical dimensions clarifies the form of each piece and suggests formal norms for the prelude as a genre.