Garrett Hardin famously proposed that coercion was necessary to avoid a tragedy of the commons. For Hardin, population growth inevitably put pressure on the environment. A contrasting perspective, informed by classical liberal political economics and the more recent new institutional economics, is that private property rights, markets, and polycentric political institutions contribute to environmental and ecological sustainability. What is necessary is a political economy of commons that recognizes institutions are the key to avoiding the tragedy of the commons. In our introduction chapter, we argue that the institutions we associate with capitalism - property rights and markets - are effective in addressing commons, especially in polycentric political regimes with robust local democracy. We argue that this is the case for resource commons, such as forests and groundwater, and for the global environment. These "neoliberal" institutions, rather than undermine commons governance, avoid tragedies of the commons.