PIP: Theoretical and empirical issues are explored as related to the extent to which population growth, particularly population redistribution through internal migration, may influence land use patterns and the deterioration of natural resources. Conceptual approaches are presented including a model of the relationships among population growth, migration, and the rural environment. Population growth has direct effects on increased demand for fuelwood and food and land fragmentation. Indirect effects exist through the demand for food which puts pressure on land extensification and intensification which affects soil quality and out migration which affect deforestation and desertification. The prevailing natural resource endowments affect the extent to which extensification of intensification of agriculture takes place in a given time period, the forms in which it occurs, and whether demographic factors play a significant role. Current trends are described for population growth and redistribution, agricultural expansion, and deforestation, desertification, and soil erosion in low-income counties. Data are for 1990 in Asia (23), Latin American (23), and Africa (39) for 85 countries with a population 1 million. Also described are cross-country relationships and the implications. In Africa population growth rates have not changed substantially and the pressure on resources is significant, while dramatic declines have occurred in east and southeast Asia, in Latin America, population growth has changed considerably. Consequences of socioeconomic development are declines in the % of gross domestic product from agriculture and the agricultural labor force. Only Thailand, Nepal, Indonesia, and North Korea out of 23 Asian countries had increases in the % of total land used for agriculture and this resulted in deforestation. Levels were already high in 1965, with 8 countries having 20% of land in agricultural use and 4 countries having 15% in agricultural use. In Bangladesh and Indian 50% of land is used for agriculture. Latin American has lower levels of agricultural land use; Bolivia and Paraguay increased land use by 100%, Nicaragua, Bolivia, and Paraguay by 50%, and 8 others by 20-50%. Africa has a small amount of agricultural land, with only 10 countries having 15% in agriculture. Irrigation and fertilization patterns are also described. Scattergrams are used to express the relationship between deforestation and increase agricultural land. The policy implications are specifically identified, and in general better data within countries and micro data (household surveys) are needed on resource depletion; national accounts need to include an appropriate computation for this.