Four experiments examined the effects of the number of alternative responses on the lateralized readiness potential (LRP), a measure of hand-specific response activation derived from electroencephalographic activity. In Experiment 1, two- versus six-choice tasks differed in both the time from stimulus onset to LRP onset and the time from LRP onset to the keypress response, suggesting that the number of alternatives influences the durations of processes both preceding and following the onset of hand-specific response activation. Experiment 2 included four-choice tasks with three alternative responses on one hand and one alternative response on the other hand; the number of alternatives on one hand influenced the duration of processes following LRP onset for responses made by that hand, whereas it influenced the duration of processes preceding LRP onset for responses made by the other hand. Experiment 3 showed that the effects of response probability are too small to be fully responsible for the effects of the number of alternatives. Experiment 4 varied the compatibility of stimulus-to-finger assignments within a hand. This influenced primarily the durations of processes following LRP onset, suggesting that hand-specific response activation begins before the response finger has been selected. Overall, these results suggest that the number of alternatives can influence the durations of processes both preceding and following the onset of hand-specific response activation, and they illustrate the utility of the LRP for the localization of factor effects within information processing tasks.