Book excerpt: The scale and severity of our environmental challenges are quickly becoming apparent. The Indian Ocean region features many places particularly vulnerable to the effects of environmental degradation and climate change, which will have profound social, economic, and cultural impacts. The increasing preoccupation with the state of the environment is also having significant political effects, including on the concept and content of citizenship. The language of citizenship has permeated environmental discourse and, conversely, environmental issues are often articulated in the language of citizenship. This book explores environmental citizenship and civil society responses to environmental challenges in the Indian Ocean region. The articles provide practical insights to improve resilience and adaptation, as well as conceptual insights into the nature of environmental citizenship discourse and practice across this vast region, from Mauritius to Malaysia. The volume showcases the complex field of environmental citizenship through a wide range of approaches, and alongside closely related concepts, such as environmental governance, environmental education, environmental justice, and corporate social responsibility. In essence, the book provides a rich, diverse and multidimensional picture of environmental citizenship in the Indian Ocean region. The chapters in this book were originally published as a special issue in the Journal of the Indian Ocean Region.