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 present a model where heterogeneous districts choose both whether to experiment and the policies to experiment with. Since districts learn from each other, the first-best requires that policy experiments converge so that innovations are useful also for neighbors. However, the equilibrium...