This Four-Volume Set explores the locations where the environment matters most - such as where people are poor, where environments are under threat (such as on frontiers), where there are few natural resources remaining, and where industrialization is rampant. It will also explore these concerns at different system levels, from local-community, to regional, national and global. It will also explore costs of damage to the very resources on which economies rely, and the values of environmental goods and services and the controversies surrounding such valuations. It is organised around environment-people interactions (livelihoods, poverty, income, economic growth); environment-environment interactions (do people matter?); and people-people interactions (collective action challenges, institutions). These interactions can be one-way and extractive, or two-way and mutually-shaping. The papers will also address the question of knowledge about the environment - what do we know? How does information change? In what form is it legitimate? How do we tell stories about the environment, and how do these shape our own world views?