This is the author accepted manuscriptWe experimentally analyze the e ect of the endogenous choice of sanctioning institutions
on cooperation and migration patterns. Subjects are assigned to one of two groups, are
endowed with group-speci c preferences, and play a public goods game. We compare
an environment in which subjects can move between groups and vote on whether to
implement sanctions, to one in which only one group is exogenously endowed with
sanctions. We nd that the possibility of voting leads to a more e cient partition of
subjects across groups, higher payo s, lower inequality, and lower migration rates. Over
time, subjects tend to vote for institutions
