In an age of post-truth politics, where official science is increasingly under attack, what is the role for grassroots citizen science in environmental justice campaigns? The environmental justice movement has traditionally rallied against the misuse of science, but it remains committed to 'science' itself. From e-waste extraction in urban Ghana to 'deeply participatory' citizen science in Southern France; and from toxic tours in Ecuador to air pollution activism in Antwerp, this book traces the complicated nexus of citizen science and environmental justice across a range of local, regional, and national scales. Together, these interdisciplinary contributions ask critical questions about how to overcome widening environmental inequality around the world, pushing the analytical boundaries of existing concepts and practices within the environmental justice movement.