Each year the Social Security Administration forecasts the financial status of the Old-Age, Survivors, and Disability Insurance (OASDI) programs by projecting trends in key variables such as the labor-force participation and earnings of the U. S. population. In the difficult task of projecting the long-term financial status of Social Security, assumptions are made concerning the relationship of immigrants to Social Security. An important aspect of that relationship is the emigration of immigrants. This article describes the general assumptions related to the level and timing of emigration that underlie projections of Social Security's financial status and examines how closely these assumptions fit research findings based on a variety of data sources. Previous trends in emigration and factors that may affect current and future levels of emigration are described. The article also presents theoretical expectations and empirical evidence concerning the timing of emigration.