This book offers an extensive critical overview of eco-socialism, one of the most generative and significant aspects of contemporary debates within socialism. Marxism has played a foundational role in the development of ecosocialism since its inception and has also led to critical reflections on the 20th century Marxism and ecological interpretation of Marxist writings. Despite the relevance of ecosocialism to the pressing debates on the ecological crisis and the growing literature on ecosocialism, there has not been a comprehensive account on ecosocialism and its variations. This volume seeks to fill this important gap and to pave the way for a more systematic development of this emerging paradigm. The book not only engages with a critique of other non-socialist ecological schools of thought in defence of ecosocialism, but also provides a critical overview of debates within ecosocialism and of ecosocialism itself. The latter includes an appraisal of ecosocialism in Bolivarian Venezuela and the implications of current efforts in the People's Republic of China to build an ecological civilisation. Furthermore, the book contains a crucial discussion about the relation between eco-socialism and indigenous studies and movements.