This primer provides guidance on presenting evidence about the economic, development, and poverty reduction benefits of the environment to public sector decision-makers, so as to justify and promote “environmental investment”. Environmental investment is taken to mean the effort, attention, and material support accorded to environmental sustainability in public budgets, policies, and planning. This includes ensuring that sufficient government funds are allocated to the agencies responsible for environmental management and conservation; that environmental goals are prioritized and incorporated into (and not undermined by) macroeconomic and sectoral policies and the instruments that are used to achieve them; and that economic and development projects and programmes factor environmental costs and benefits into their calculations, and do not impact negatively on the environment.