The Shape of Things to Come provides valuable new insights into the programs and investments that can make countries "healthier"-more stable and peaceful, more democratic, and better able to provide for the needs of their citizens. It places all countries into one of four major age structures with attendant characteristics, benefits and risks associated with governance, security and economic development.

The world's population more than doubled in the last half-century and still is increasing. Absent an unexpected dramatic shift in family size or catastrophic increases in death rates, it could add 2.5 billion people before peaking. Worldwide, the largest group of young people ever is entering their reproductive years, requiring an expansion of family planning services to enable more couples to have the smaller families and later pregnancies they desire. In the long term, this will contribute to individual and family well-being, a slowdown in population growth and sustainable economic development.

Population age structure-the comparative size of specific age groups relative to the population as a whole-can help illustrate where countries' risks and opportunities lie in relation to critical issues such as democracy, development and security. In fact, the influence of age structure on a state's governance, risk of an outbreak of civil conflict, and economic development is both significant and quantifiable. Given these linkages, investments in family planning, infant and maternal health, education and economic opportunities for girls, women and young people can vastly affect the shape of things to come.

In 1994, at the International Conference on Population and Development (ICPD), 179 nations agreed on a plan for achieving universal access to basic reproductive health care by 2015. Today, vast differences remain in reproductive health status between rich and poor countries. The HIV/AIDS pandemic exacts a growing toll in human lives and threatens economic growth in some of the world's poorest countries. Donors focused on achieving the Millennium Development Goals – and concerned with poverty reduction, human rights, health and development – must help ensure the adequate flow of financial resources (referred to as population assistance) for sexual and reproductive health services.

Population growth around the world affects Americans through its impact on the economy, the environment, and safety and health, and the habitability of the world our children will inherit. While tracing cause and effect is difficult the evidence is accumulating that current rates of population growth pose significant and interacting risks to human well-being and are a legitimate concern for Americans.