Analysis and comparison of the String Quartet in E minor (1936) and the Second String Quartet (1951) (which are the only two string quartets written by Roger Sessions) reveals important aspects of Sessions’ compositional style and how certain of these aspects undergo change over the fifteen years separating the quartets. The two quartets have more similarities than differences in style. In both works form is clearly demarcated by very traditional associations of musical ideas, the music depending upon developmental procedures for its direction. Tension is controlled through careful contrasts of tempo, motion, texture, rhythm, consonance and dissonance, melodic contour and range, etc. The various climaxes and cadences in the two pieces also reveal the same procedures. Finally, both works display long, often-elided phrase constructions. The most important stylistic difference between the two quartets is that the Second String Quartet presents and develops fewer ideas per movement and has more movements (although approximately the same number of bars). In broad terms the quartet may therefore be described as embodying greater control of fewer resources than its predecessor. One of the principle differences between the two quartets might seem to be the use of key in the String Quartet in E minor but not in the Second String Quartet. In fact, this difference is of little significance to the writing style common to both works, since each is highly chromatic. In the earlier piece only large-scale harmonic progressions may be analyzed with any degree of accuracy; chord-by-chord analysis is virtually impossible because the tonal relationships are too complex. In comparison to the String Quartet in E minor, the Second String Quartet represents not a turning away from, but a growth beyond the use of tonality. Thus, in its own way, Sessions' development as a composer parallels that of Arnold Schoenberg in the early years of the twentieth century, and reinforces the example of artistic craftsmanship that serves, rather than hampers, expression.