Agricultural change cannot be understood separately from the general process of development, and may be misleading if taken as a guide to either the nature or the extent of that process. This is because throughout most of the Third World agriculture is a fundamental economic activity which has to respond to a variety of both external and internal forces merely to ensure survival. Most increase in the productivity of Third World agriculture has done no more than that, and there has in this century been little rise in the real incomes of farmers despite widespread evidence of ‘modernization’. One of the most important problems affecting agricultural development is the cost of the infrastructure, which is in itself a major industry attracting labour and other resources to it. This infrastructure must play a vital role in agricultural change, for higher productivity in most of the countries concerned must involve increasing dependence on the market.