The logical basis and mathematical character of a short method for making population projections by age from one decennial census to another is discussed. The method is based on the assumption that age-specific vital rates and migration rates of the recent past will continue unchanged into the near future, i.e. from the last decade through the next decade. The method includes techniques for making projections of the population under 10 years of age at the end of the decade ahead. An illustrative example is presented and an IBM 650 Program has been prepared.