This paper outlines the current state of anticipatory action and discusses some of the existing evidence on its impact. It is not intended to provide a comprehensive literature review or a meta-analysis of the impacts of early warning or early action initiatives. Rather, it presents some examples of different types of impact associated with a range of anticipatory action in developing countries. This is in recognition of the diversity of anticipatory action mechanisms and variety of activities being implemented in different contexts, as well as the range of studies that have been carried out focusing on different outcomes. The paper also highlights evidence gaps and points out some of the methodological challenges in measuring impact.