Playing the guitar develops manual habits but also habits of thought. For example, guitarists often conceptualize chords as two-dimensional shapes—an approach that is foreign to pianists. What does it mean, then, to think like a guitarist? This presentation approaches “guitar thinking” from music theory and cognitive science. Recent work in transformational theory examines fretboard space, formalizing physical patterns instead of sounding ones. Yet the guitar is both an object of music-theoretical inquiry and also a music-theoretical tool. From the late sixteenth century to the present, guitars have been used in the production of musical knowledge and discourse. Epistemic aspects of the guitar, moreover, can be illuminated through psychological research. For example, experiments help reveal visual and tactile aspects of guitar thinking. This sensorimotor interplay can be theorized in terms of grounded cognition, and it points to the role of technology and technique in musical experience.