More than thirty years after the collapse of the USSR, the critique of state socialism is still used to deny alternatives to capitalism, irrespective of global capitalist ecological and social devastation. There is seemingly nothing worthwhile salvaging from decades of state socialist experiences. As the climate crisis deepens, Engel-Di Mauro argues that we need to re-evaluate the environmental practices and policies of state socialism, especially as they had more environmentally beneficial than destructive effects. Rather than dismissing state socialism’s heritage out of hand, we should reclaim it for contemporary eco-socialist ends. By means of a comparative and multiple-scaled approach, Engel-Di Mauro points to highly diverse and environmentally constructive state socialist experiences. Taking the reader from the USSR to China and Cuba, this is a fiery and contentious look at what worked, what didn’t, and how we can move towards an eco-socialist future.