Having laid out the critical importance of finance to energy transitions, this chapter briefly explores the historical role of finance capital in fuelling energy booms and the growth of the fossil fuel economy, before looking at slow shifts in strategy towards a more de-stabilising role in the face of concerns about un-burnable carbon, fears about the risk of stranded assets, as well as the potential returns to be made from expanding investments in renewable energy. In the section on the political economy of finance, however, this more optimistic reading of the role of finance is nuanced by looking at the practices of finance. Finally, in the section on ecologies of finance, the chapter looks at the circulation and interconnectedness of different forms of finance, in which, despite the fetishisation of private finance, public finance still has a vital role to play in the form of aid, multilateral development bank lending and procurement. It also explores the under-acknowledged challenge for finance of energy systems which will have to restrict supply and demand if they are to be compatible with a sustainable climate future.