This chapter offers an examination of the concept of power, as it underlies the idea of hegemony and is pervasive not only in the International Relations (IR) discipline in particular, but in Political Science in general; it is divided into five sections: the first section discusses the notion of power as an attribute; the second and third take on the understanding of power as a relation, with the former reviewing its “thin” variant and the latter the “thick” one. Section four deals with the operationalization issues that come about when doing power-centered empirical analysis. A final section summarizes the discussion.