Profound alterations to instruments that take place over short periods of time are fascinating, and the changes undergone by the guitar during the late eighteenth century make for an intriguing transition in the instrument's history. The guitar that existed before 1750 is most commonly referred to as the 'Baroque guitar' and is vastly different from the guitar of today. It was considerably smaller than the guitars that followed, pitched higher, and used primarily for accompaniment through chord strumming. From roughly 1750 to 1800 the guitar underwent a transformation that eventually led to the design and performance practices that have continued through to this day; larger, with lower-pitched courses (and sometimes single stringing), and used increasingly more in punteado (plucked) style. By defining the instrument as it existed prior to 1750, and the changes that it underwent after 1750, we can ensure that the instrument discussed is the one that has directly led to the instrument we use today. Because instrument design and performance practice inevitably influence each other, a thorough examination of ornamentation practices from 1750-1800 can lead to a greater understanding of the instrument as it changed, and the instrument it eventually turned into. Since the early nineteenth century was one of the more productive time periods for the guitar, having a better understanding of the ornamentation performance practices that preceded it may provide insight to how the players and composers of this fertile time (Sor, Aguado, Giuliani, etc.) approached their instrument. Although there was not much music printed or copied for guitar during the latter half of the eighteenth century, a substantial number of guitars were built, along with instruction manuals featuring the guitar. Instruction manuals were examined, along with works for solo guitar and guitar in ensemble with other instruments, to explore ornamentation practices from 1750-1800. Through examination of the guitar instruction manuals of the late eighteenth century, an increased understanding is gained regarding the techniques that eventually became cornerstones of nineteenth-century guitar performance practice.