Mobility of the factors of production, important in enabling appropriate responses to be made to changes in world market conditions, is absent in the case of many developing countries. Evidence of structural rigidity may be provided in a general way by persistently adverse movements in the terms of trade, but it may also manifest itself specifically in over-production or under-production of particular commodities and in excessive dependence on slow-growing export commodities. The process of development is seen as generally involving a shift in the structure of production towards manufacturing activities, producing intermediate and capital goods, and the provision of different kinds of services.