The study presented here was designed to answer the question of whether or not amphetamine sulfate ("pep pills") improves athletic performance in trained athletes. Preliminary Considerations Controlling Factors in Planning.— We knew at the outset that many variables might influence the effect of amphetamine on athletic performance: dose level; time after medication at which event was performed; whether the subject was rested, slightly fatigued, or severely fatigued; type of athletic event performed (brief intense effort versus prolonged, less intense effort, or event where performance is largely dependent on form versus event where performance is largely dependent on strength); whether the subject performed the event competing with the clock or competing with another athlete; whether the athlete knew he was receiving a drug (and his expectations concerning its effect); whether or not the subject was in top form; mood; and motivation. An initial exploratory phase of the investigation yielded data which