Anton Webern’s Op. 18 stands at nearly the exact center of his published work. Though it was in his Op. 17 that Webern began working with ordered pitches, there are some logistic struggles evident in his diversions from the row throughout that work. It is in Op. 18 that Webern first consistently uses a row in its complete, unchanged form. His increasing mastery of this style of composition is shown throughout Op. 18, a collection of three songs; the first with a single row repeated with no permutations of any kind; in the 2nd song, inversions and retrograde are introduced; and in the final song Webern experiments with simultaneous unique row forms for each instrument. These songs feature a guitar, E-flat clarinet, and soprano voice, with the first song a setting of a folk text. In this dissertation I argue that Webern’s later style–his orchestration, harmonic progressions, and formal structures–grows out of his choice of guitar as harmonic foundation in Op. 18. In my analysis I look at row construction and usage, as well as orchestrational considerations, folk implications, text setting, and specific voice-leading properties of Webern’s Opp. 18, 25, and 30. In so doing I will uncover a link between Webern’s pivotal Op. 18 song cycle, with the guitar playing a central role, and many of his compositional choices in his later works. My analysis looks at Webern’s works through the lens of a guitarist. I will explore the piano accompaniment of Op. 25 as if it were written for guitar, and do the same for his Op. 30 Variations for Orchestra. These analyses will show that his later works, and later style in general, have an underlying idiomatic character of guitar music. I argue that Webern’s late works feature, as a result, are his own version of folk music through their simplicity, clarity of form, and overall encapsulation of the sound of the guitar.