This paper provides an overview of issues relating to aid effectiveness. It argues that it is impossible to give a definitive answer to the question of whether aid is effective, and that it is more useful to ask what can be done to make aid more effective. The paper then groups the various determinants of aid effectiveness, as well as strategies to improve effectiveness, under three headings: the performance of the recipient (developing) country government; the performance of the aid agency of the donor (developed) country; and the interaction between the two. This provides, it is argued, a useful framework within which to understand different and competing arguments about how to improve aid effectiveness.