This research continues the perceptual evaluation of "composers' pulses" begun by Repp (1989a) and Thompson (1989). Composers' pulses are patterns of expressive microstructure (i. e., timing and amplitude modulations) proposed by Clynes (1983). They are said to convey individual composers' personalities and to enhance their characteristic expression when implemented in computer performances of their music. For the present experiments, the initial bars of five piano pieces by each of four composers (Beethoven, Haydn, Mozart, and Schubert) were generated with each of four pulse microstructures similar to Clynes's composer-specific patterns, and also in a deadpan version. Listeners representing a wide range of musical experience judged to what extent each computer performance had the composer's individual expression, relative to the deadpan version. Listeners showed an overall preference for the Beethoven and Haydn pulses. The pattern of pulse preferences varied significantly among individual pieces, but little among different composers. These results indirectly support the general notion that expressive variation is contingent on musical structure, but they offer little evidence in support of fixed, composer-specific patterns of expressive microstructure.