Abstract
This paper reviews the basic theories underlying the current practice of the United Nations and other international population projections covering the less developed countries, particularly those of Southeast Asia. In the field of demographic projections, the most basic frames of reference for assumptions on the future course of fertility and mortality are the demographic transition theory and threshold hypothesis, but other than these very little use has been made of population theories. Not much has been done so far to incorporate socioeconomic factors within the framework of population projections. This paper explores the reasons why and tries to find ways to utilize some new developments in population theories by Caldwell and Knodel.
