The booklet starts with a general overview of how illicit drugs and the environment are linked within the bigger picture of the Sustainable Development Goals, climate change and environmental sustainability. It highlights direct and indirect linkages and gives examples of the significant local and individual-level impact that drugs can have on the environment. This is followed by a more in-depth overview of the latest scientific evidence for plant-based drugs and for synthetic drugs. For plant-based drugs, for example, this includes an analysis of the relationship between illicit crop cultivation and deforestation. For synthetic drugs, it includes an analysis of waste composition, volumes, and dumping and discharge, as well as the relation with wastewater treatment.