The population problem in third world countries is influenced by various factors. High fertility rates are not due to irrational behavior, but a rational response to high infant mortality rates. Improving education, health, and social conditions is crucial to reducing fertility rates. Economic development and population growth are closely linked, with development leading to increased population growth and reduced per capita income. In developed nations, economic development and reduced mortality rates occurred simultaneously, stimulating further economic growth. In developing countries, reduced mortality rates and high consumption aspirations have preceded economic development. To address the population problem, efforts are needed in family planning, education, health, worker skills, technology, capital accumulation, and economic reorganization.