The relationship between development finance and climate finance is a key political issue. Some (particularly least developed country (LDC) climate negotiators) stress the differences. Others (most bilateral development agencies) stress the similarities. But understanding this relationship has now become urgent. We must distinguish between different types of international climate finance (adaptation and mitigation) and recipients of these funds (LDCs versus middle-income countries). In LDCs, links between adaptation finance and development finance are strong and so this should be counted as official development assistance (ODA). But in middle-income countries, links between mitigation finance and development finance are weak, so instead this should be additional to ODA and counted as the new metric of total official support for sustainable development (TOSD).