In response to concerns about the adverse consequences of rapid population growth, family planning programs have been implemented in many developing countries. The aim of the present study is to assess the impact of this programmatic approach on long-range population growth. The result of a new and hypothetical population projection indicates that in the absence of family planning programs the population of the developing world could be expected to reach 14.6 billion in the year 2100 instead of the 10 billion that is currently projected by the World Bank. Despite the apparent success of existing interventions, fertility control is far from complete, as many women continue to bear unwanted births. To assess the impact of this unintended childbearing a second hypothetical projection is made. With perfect implementation of reproductive preferences, the population size of the developing world in 2100 would be reduced by an estimated 2.2 billion below the current projection. Further strengthening of family planning programs and improvements in birth control technology are therefore likely to provide important demographic benefits.