Education systems are essentially national. The national level is a natural scale at which to consider the nature and functioning of the system and how it affects the life and work of the population within the area of the state. With very few exceptions (notably Switzerland and, in some respects, the United States) the essential structures of the education system, its length and curriculum, the qualifications and salaries of teachers, and the means of finance are all set nationally. Though there can be important differences within countries, and many of these will be explored in this chapter, they are constrained by the national framework set for the system by the sovereign governments. As was argued in the previous chapter there are large and important differences between countries, even neighbouring countries, in the structures and organization of education, such that inter-country differences are likely to be much greater than intra-country differences. Yet it was also argued that, as a result of external pressure from multinational lending and planning agencies, notably the World Bank and UNESCO, these international differences in both quantity and quality have been reduced in recent decades. Despite this trend, they remain greater than differences within most Third World countries. The range of experience examined in the previous chapter in terms of crude levels of enrolment or of quality in terms of measured achievement, or of levels of expenditure is normally much less between each region but not necessarily between each school within each country.