Sexual conflict occurs when the genetic interests of males and females diverge. Recent evidence supporting the view that male and female genomes are in conflict has now revolutionized the way in which we interpret interactions between the sexes, and suggests that sexual conflict is a potent force in male–female coevolution. Here, we consider the nature of sexual conflict and what distinguishes it from models of coevolution by sexual selection. There are advantages and pitfalls to the various experimental and comparative approaches now used. More precise predictions derived from theory are essential to evaluate much of the empirical data in support of sexually antagonistic coevolution. Equally, there needs to be a mechanistic understanding of the traits underlying sexual conflict to formulate and test these predictions.