Zero population growth (ZPG) is a demographic term that refers to a population that is unchanging, meaning it is neither growing nor declining, and the growth rate is zero. This demographic balance could occur when the birth rate and death rate are equal, but it also accounts for immigration and emigration. Therefore, a country that has reached zero population growth has a population where births plus immigration is equal to deaths plus emigration over the course of a year. Achieving ZPG is often a goal of demographic planners and environmentalists who believe that reducing population growth is essential for the health of the ecosystem. However, it is difficult to achieve because a countrys population growth is often determined by economic factors, incidence of poverty, natural disasters, disease, etc. .

The American sociologist and demographer Kingsley Davis is credited with coining the term ZPG, but it was used earlier by George J. Stolnitz, who stated that the concept of a stationary population dated back to 1693. ZPG is often associated with environmentalism and preserving cultural traditions and ethnic diversity, as allowing human populations levels or rates to fall too low can have negative consequences.

Population Connection, formerly known as Zero Population Growth, is the largest grassroots population organization in the United States, and it advocates for stabilizing world population at a level that can be sustained by Earth’s resources. The organization was founded in 1968 by Stanford entomologist Paul Ehrlich, author of the 1968 book The Population Bomb, who argued that it was time for a population-control movement to prevent shortages of food, water, and more.