study of them, but this complexity all-too-frequently is unfortunately not recognized. No subject requires to be approached in more truly interdisciplinary fashion if any worthwhile understanding is to be achieved. Whatever our disciplines may be, concern with people in the developing countries will be related at least to some extent to the problems arising from rapid population growth and the limited resources available to meet the basic needs for food, shelter and clothing. Overall growth rates, consequent on reduced mortality and maintained high fertility, range between 2 to more than 3% per annum and are sufficient to result in the doubling of population within a generation or a little more. These rates make the major contribution to a rise in world population from a present 4,000 million to a total in the first decade of the twenty-first century estimated to range between 8 and 13,000 million. What estimate is reached will depend on the parameters used to project, for it is impossible to predict, population in the future. Demographers rightly insist on this distinction for the variables involved are complex, and as with the majority of human variables they may be subject to considerable change over quite short periods of time. Furthermore, for the majority of the less-developed countries the data available for projection are limited and deficient While there have been some reductions in fertility rates among populations in some less developed countries these are still limited. Many of the patterns for population in the early twenty-first century are established by those who are already born, short that is of revolutionary changes in fertility patterns which are unlikely or of cataclysmic changes in mortality which are fearful to contemplate. As was made clear from the stand taken by less developed countries at the UN Population Conferences in Bucharest in 1974 and in Mexico in 1984, the answers to population problems do not lie solely in reducing numbers by pouring in more money for birth control and family planning. People must be motivated to accept these measures, to use them effectively and on a large enough scale to make any real impact. The problems are not simply associated with numbers of people, but are concerned more fundamentally with poverty and with levels of socio-economic development. It has been said of the Bucharest conference that it "drove a stake into the heart of Malthus" and the World Plan of Action produced from the conference asked that: "Efforts made by developing countries to speed up economic growth must be viewed by the entire international community as a global attempt to improve the quality of life for all people In medium and longer term strategies the need to reduce fertility will continue, in the short and in medium terms more consideration must be given to the third and most neglected component of population change, conventionally called migration, an umbrella