This article is a synopsis of a UN study, with emphasis on Italy and the United States. In March, 2000, the United Nations Population Division published a 143-page booklet entitled, Replacement Migration: Is It a Solution to Declining and Aging Populations? Five projections were developed for eight countries: France, Germany, Italy, Japan, Republic of Korea, Russian federation. United Kingdom and United States, and also for Europe and the European Union ; i.e., current projections, current projections with zero immigration, migration required to offset projected population declines, migration required to offset projected declines of working age population (16–64 years), and migration required to prevent any decline in the ratio of the working age population to the old age population (65 years or older). Key findings: demographic shrinking and aging will be accompanied by economic, social and cultural disruptions that can only partially be offset by immigration.