The present study investigates the effect of a change in instrumentation on the recognition of musical excerpts in Western contemporary and tonal music. The critical finding was a strong effect of timbre on the recognition of musical material that is modulated by both the extent of musical expertise and the musical style. Changing the instrumentation of musical excerpts from a piece by Reynolds considerably hampers recognition among musicians (Expts. 1 and 2), but not among nonmusicians, whose recognition was poor regardless of instrumentation. Both musicians and nonmusicians were affected by instrumentation change in excerpts from a symphonic poem by Liszt (Expt. 3). This finding suggests that timbre may contribute, along with pitch and rhythm, to the identity of musical materials. The difference found between musicians and nonmusicians with the Reynolds piece may be parsimoniously explained by the fact that the musicians were considerably more familiar with contemporary music than were the nonmusicians.