Although the world demographic transition from high to low fertility appears to be nearing its completion, observed in perspective, this is the latest in a series of such transitions stretching back into prehistory. A stable new equilibrium is far from inevitable; indeed, it is unlikely. Many countries are experiencing below-replacement-level fertility, and this trend is spreading. Couples are now able to choose their family size, free of the traditional pressures to bear children that was characteristic of most traditional societies. In fact, most societal pressures for the last generation have been distinctly antinatalist, in response to the enormous attention paid by the media to the "population bomb" agenda. This antinatalist attitude is changing, however, and what seems more likely than either a stationary or declining world population is a new growth cycle reflecting a resurgence of fertility as a response to growing material affluence and potential technological mastery of environmental challenges. Societal pressures and policies will play a role in this transition as they did in earlier ones.