This chapter introduces the concept of Temporal Focal Points in explaining change in international institutions. In doing so, it elaborates theoretically the arguments contained in the introductory chapter. It models the coordination challenge facing states as a stag hunt game, where international actors can all benefit if they are able to cooperate. In hunting stag – or, engaging in institutional change efforts – actors can move to a Pareto-superior, payoff-dominant equilibrium. The challenge that they face is that if they hunt stag and others do not, they will expend scarce assets and end up significantly worse off. The risk of acting cooperatively when others do not leads actors to persist at inferior, risk-dominant equilibria. This can change suddenly, however, when actors reach a temporal convergence of expectations. The convergence is often facilitated by the arrival of Temporal Focal Points. The heightened probability of successful coordination leads to sharp increases in political and analytical investments. The chapter concludes with a discussion of methodology and case selection.