In the present article, we discuss and compare recent theoretical and empirical contributions to the growing body of research on social power. In the last decade, five different theories on power have been proposed. These theories can be distinguished according to whether they focus on intrapersonal, interpersonal, intergroup or ideological processes. Our analysis leads us to claim that future theoretical contributions would have much to gain by addressing the issue of social power on multiple levels of analysis. The recent empirical work on social power suggests that powerful individuals and members of powerful groups differ from powerless individuals and members of powerless groups with regard to (a) how they perceive and judge others, (b) how they are evaluated as targets, and (c) how they behave. Those who have power perceive others more stereotypically and judge them more negatively. They also tend to take action more frequently and generally behave in a more variable manner. This difference in objective variability is further reinforced by perceivers' tendency to exaggerate the variability of high power groups. The latter two effects contribute to the phenomenon that high power groups are less often the target of stereotypes than low power groups. Copyright © 2006 John Wiley & Sons, Ltd.