When external effects are important, markets will be inefficient, and economists have considered several broad classes of economic instruments to correct these inefficiencies. However, the standard economic analysis has tended to neglect important distinctions and interactions between the...

Favor trading is common. We do something nice for someone and they do something nice in return. Several motives might underlie such behavior, including altruism, strategic motives, and direct or indirect positive reciprocity. It is not yet well-understood how these fit together to affect...

Some policy problems pit one group׳s interests against another׳s. One group may determine provision of a project (such as a dam) that benefits group members but hurts others. We introduce a model of such projects. In-group members may contribute to a common fund that benefits them as a public...

Temporal spillovers occur when a conservation program changes what happens to land outside the temporal window of the conservation contract. This may happen when conservation improves land so that returns to non-conservation uses are increased, or when landowners’ preferences become more...