Senior fellow Michael Clemens was interviewed by the BBC World Service on the economic benefits of migration.
From the interview
The voices of ordinary Greeks - those struggling to hold things together in these difficult times - are not normally heard.
Coverage of Greece's economic problems is all too often dominated by images of ferocious riots and striking workers.
There is no question that wave after wave of wage-cuts and tax rises have generated a lot of anger, but the truth is that most Greeks haven't taken to the streets.
So, as the austerity measures bite ever deeper, how are these people being affected? The BBC's Europe Business Correspondent Nigel Cassidy reports from Athens.
Plus, what Greece and the other economies of the eurozone really need is economic growth to raise incomes and tax revenues and - the hope is - to begin to erode away those vast deficits.
Unfortunately most are experiencing - at best - stagnation.
So what could kick start growth? A recent survey by the American economist Michael Clemens of the Centre for Global Development suggests one answer could be migration. He concludes that the economic gains from freer migration would dwarf the gains from, say, freer trade - so long as the benefits to the migrants are included.
Justin Rowlatt asked him why migration can bring such big economic benefits.
Listen to it here.