Economic development and national wealth is only part of the reason, however, and perhaps not even the most important part. Sri Lanka and Costa Rica have more effective and service oriented political administrative systems than many countries that are much wealthier. Planned educational systems are often without classrooms, teachers or supplies in the rural areas. Primary health services often do not reach the rural areas. National governments have the capacity and responsibility to organize local units so that they will be active participants in the promotion of sustainable development. It is especially important that the national government decentralize control, to give local units a wide degree of latitude in adapting national plans to specific local conditions. Integration is one of the most common terms found in plans and attempts to link different specialized functions. Population or a family planning programme might be integrated with health by placing it in a ministry of health.