PIP: This article sets forth 3 positions on population growth: 1) rapid population growth is a central development problem that implies lower living standards for the poor; 2) proposals for reducing population growth raise difficult questions about the proper domain of public policy, yet it is acceptable for governments to attempt to influence private decisions about family size; and 3) the experience in many developing countries shows that quick, effective measures can be taken to reduce fertility. Rapid population growth has slowed development because it exacerbates the difficult choice between higher consumption in the present and the investment needed to bring higher consumption in the future. As populations grow, larger investments are needed just to maintain current capital/person. It further threatens the balance between natural resources and people and creates severe economic and social problems in urban areas. Public policy must provide alternative ways for poor families to secure the benefits provided by large family size. That is, governments need to provide tangible evidence that it really is in the best interests of parents to have fewer children. Also required is greater infomation about and access to fertility control. When family planning services have been widespread and affordable, fertility has decline faster than social and economic progress alone would predict. There is a need for immediate action to improve women's status and to make education, family planning, and primary health care more available. Although economic and social progress help to slow population growth, rapid population growth hinders development. Thus, governments must act simultaneously on both fronts. Accumulating evidence on population growth in developing countries shows that is the combination of social development and family planning that reduces fertility.