For a club such as the European Union, an important question is when, and under which conditions, a subset of the members should be allowed to form "inner clubs" and enhance cooperation. Flexible cooperation allows members to participate if and only if they benefit, but it generates a freerider...

We analyze participation in international environmental agreements (IEAs) in a dynamic game where countries pollute and invest in green technologies. If complete contracts are feasible, participants eliminate the hold-up problem associated with their investments; however, most countries prefer...

We analyze participation in international environmental agreements in a dynamic game in which countries pollute and invest in green technologies. If complete contracts are feasible, participants eliminate the holdup problem associated with their investments; however, most countries prefer to...

We develop a model of policy experimentation in federal systems in which heterogeneous districts choose both whether to experiment and the policies to experiment with. The prospect of informational spillovers implies that in the fi rst best the districts converge in their policy choice....

We analyze participation in international environmental agreements (IEAs) in a dynamic game where countries pollute and invest in green technologies. If complete contracts are feasible, participants eliminate the hold-up problem associated with their investments; however, most countries prefer...