Climate Change is the most significant challenge to achieving sustainable development in ACP countries. With limited availability of domestic or international finance, ACP countries need to stimulate private investment for climate change adaptation. Improving the business environment for climate adaptation is key to unlocking private sector development and investment by the private sector in sustainable development. To focus investment climate and business environment reforms in a way to maximise the mobilisation of investment for climate adaptation, ACP countries need to prioritise sectors and businesses where there is a clear business case and return on investment for the private sector. By understanding the different needs of these businesses – from micro agricultural enterprises, to large water utilities and financial institutions – investment climate reforms can be tailored to unlock investments and accelerate climate adaptation.