The degree and basis of social power of uniformed figures was investigated in two field experiments. In the first experiment, subjects were stopped in the street by an experimenter dressed in one of three ways: a civilian, a milkman, or a guard. They were asked to pick up a paper bag, or to give a dime to a stranger, or to move away from a bus stop. The results indicated that the subjects complied more with the guard than with the civilian or milkman. In the second field experiment, designed to examine the basis of the guard's power, subjects were asked to give a dime to a stranger under conditions of either surveillance or nonsurveillance. The guard's power was not affected by the surveillance manipulation. A logical analysis of social power indicated that the guard's power was most likely based on legitimacy. Two questionnaire studies indicated, however, that college students did not perceive the guard as having either more. power or more legitimacy than the milkman or civilian. The nature and importance of understanding legitimacy was discussed.