This paper considers the principal economic arguments surrounding the fact of rapid population growth in developing societies. It suggests that the extent of controversy which has attended this topic in the past can be greatly reduced by identifying precisely the indicators in respect of which the economic effects of population growth are judged. If indicators of individual well-being are chosen, the effects are likely to be negative in most cases. For other indicators the outcomes are less clear. The paper also examines some of the principal national and global issues affected by population growth, and suggests that it is not population alone, but the relations between population and income growth and technological and policy choices, which have to be understood if the 'population problem' is to be seen in true perspective. Prospective population growth can be accommodated; but institutional and political capacities will be severely tested by it, and could prove inadequate. Most countries, and the world as a whole, would certainly be better off if population were to grow more slowly.