This paper provides evidence on immigrants performance and impact in the U.S. labor market. We document that new immigrants do bring fewer marketable skills to the United States than did earlier cohorts and that changes in the source countries of recent immigrants account for all of this decline in immigrant quality. We find no important evidence that quality has declined within immigrant ethnic groups. We also show that immigrants assimilate rapidly in the U.S. market (10 years of U.S. experience offsets most of the earnings disadvantage of new immigrants) and that assimilation is more rapid for groups who start with lower initial wages. (EXCERPT)