This volume completes and brings to a climax this definitive compendium of readings in honor of Elinor and Vincent Ostrom. It contains pathbreaking essays by the Ostroms and others on polycentric governance, climate change, sustainability and other vital issues. It travels well beyond Lin’s famous work on common-pool resources, but it extends analytical frameworks that she originally developed in that context. This work is on the frontier of discovery in social science and it addresses several of the most urgent problems of our time. It is a magnificent memorial to the Ostroms and their legacy.