As the impacts of climate change grow more severe and frequent, greater adaptation action is increasingly urgent. International providers have a pivotal role in providing and mobilising finance flows to support adaptation in developing countries, which often lack resources and capacity to undertake adaptation measures. This chapter provides an overview of key international policy context and developments, methodological challenges in accounting for adaptation finance, various sources, mechanisms, and instruments of adaptation finance, as well as both adaptation-related financing needs and tracked finance flows. Such an overview intends to motivate the need to better identify challenges and opportunities for scaling up adaptation finance and improving its effectiveness.