Locke's account of the idea of power is thought to be seriously problematic. Commentators allege that the idea of power causes problems for Locke's taxonomy of ideas, that it is defined circularly, and that, contrary to Locke's claims, it cannot be acquired in experience. This paper defends Locke's account. Previous commentators have assumed that there is only one idea of power. But close attention to Locke's text, combined with background features of his theory of ideas, supports the drawing of a (...) distinction between four different ideas of power. The paper describes each idea and its role in the Essay. It then argues that this distinction can help Locke to avoid the traditional criticisms. (shrink)