Until recently, luthiers have been conservative in their wood choices for guitars and other chordophones. Most soundboards (tops) were made from American or European spruces. Rosewood and, less frequently, mahogany, maple, and koa, were used for backs and sides. Spanish cedar and mahogany were the preferred species for necks; ebony or rosewood for fretboards. Due to scarcity and increasing costs, new woods are now employed. Some are congeners of traditional woods; others are more innovative. The botanical identification of many of these species is inaccurate. A common name may refer to more than one species (under–differentiation, e.g., Madagascar rosewood for several Dalbergia spp.). Conversely, a binomial may be known by several common names (over–differentiation, e.g., European, German, or Italian spruce for Picea abies). Instrument makers and wood suppliers are unreliable sources of taxonomic names, especially with newer woods. Here, I provide the full taxonomic identification (binomials, author citations, and families) for both traditional and some new guitar woods. Many factors determine a wood’s suitability for lutherie. A model based on two mechanical properties of wood, density and modulus of elasticity, can be used to determine what species of wood constitutes each part of a guitar. Many of the “new” guitar woods are now becoming scarce. Luthiers face the continual task of finding suitable alternative woods. The model presented here can serve as a guide in future wood choices; further modifications, using additional wood properties, may help refine the model. These principles are also applicable to wood selection for other chordophones.