This paper aims to stimulate a systematic discussion about what should be the goals of aggregate level population policies in the context of population aging and shrinking in some parts of the world and continued rapid growth in others. It starts with a discussion of the shortcomings of three currently dominating assumptions: (a) the desirability of achieving replacement level fertility, (b) a demographic dividend will translate fertility declines into aggregate economic growth, and (c) only addressing the .unmet need. for contraception in developing countries will result in significant fertility declines. The paper then summarizes new empirical evidence on the interactions between changing age and education structures and their impacts on population growth, health, economic growth, democracy, and adaptive capacity to environmental change. It suggests that strengthening the human resource base for sustainable development should become the 21st century population policy paradigm.