The relationship between population growth and technological change has been debated since the end of the eighteenth century a debate whose main configuration has proved remarkably persistent. During the ensuing 200 years, historically unprecedented rates of change have been observed in both variables: in industrial, commercial, and communications revolutions spreading out from Europe, North America, and Japan; in parallel (though spatially and temporally uneven) revolutions in the technological base of agricultural production; and in a demographic transition–in which mortality decreased and fertility first increased, then decreased that is still underway in many developing countries. Interconnections there must be, yet the attribution of primacy and direction of causation among these variables, not to mention the nature of the mechanisms involved and means of influencing outcomes in the interest of meeting social goals, remain controversial. Meanwhile, a new awareness of the emergence of complex social-environmental systems, whether at local or global levels, has extended the debate beyond the discipline of economics, and broadened its emphasis from the welfare of the human race to that of the planet.