Almost everybody knows that in the past 40 years, the real wages and job prospects for low-skilled men, especially low-skilled minority workers, have fallen. And there is evidence -- although no consensus -- that a rising tide of immigration is partly to blame. Now, a new NBER study suggests that immigration has more far-reaching consequences than merely depressing wages and lowering employment rates of low-skilled African-American males: its effects also appear to push some would-be workers into crime and, later, into prison.