Immigration is transforming the U.S. labor force with important consequences for Social Security's adequacy and finances. Using longitudinal data from the Survey of Income and Program Participation matched to administrative data on lifetime earnings and benefit receipt, we measure the extent to which nonnatives' lifetime earning patterns, payroll taxes paid, benefits received, and total incomes differ from those for the U.S.-born population. We consider other outcomes important to retirement security, like health status, marital status, and financial wealth. We also compare various immigrant groups with one another. Our findings stress heterogeneity in labor force and Social Security experiences among immigrants.