Wheel running in the rat may be due to a specific activity drive or to increased activation arising from other drive states or both. Experiment 1 confirmed that rats satiated for food and water run spontaneously in the activity wheel and revealed that, under combined food and water deprivation, they run more actively than under either food or water deprivation or in a nondeprived state. Experiment 2 examined the reward properties of wheel running for satiated rats compared with animals both food and water deprived. Satiated animals learned the correct response in a T maze more rapidly than deprived animals when this meant access to an activity wheel. They also learned two position reversals and extinguished their response when denied access to the wheel.