This key sheet is part of a series of awareness raising tools developed by Irish Aid to accompany its Environment Policy for Sustainable Development. Key strategies for implementing the policy are: i) mainstreaming, where the environment is recognised as a critical part of sustainable development and is taken into account in all policies, programmes, activities and funding decisions; and ii) partnership, where Irish Aid works with national governments, multilateral organisations, international agencies and civil society organisations to contribute to sustainable development. The first step in environment mainstreaming is to understand how the environment is linked to the development challenge or sector YOU are responsible for. In this key sheet, we describe why the conservation and sustainable use of biodiversity is essential to poverty reduction, and suggest sources of additional information. More detailed guidelines on mainstreaming environment and development will be produced at a later date.