Planning practice has shown progressive refinement in its style and methodology, reinforced by the development of specialist skills and their mutual integration in the planning profession. The planning profession in the Netherlands exhibits no formal patterns of affiliation. The actual style of planning in the Netherlands is a mixture of strategic and negotiative elements. City planning in the Netherlands is characterised by a strong involvement of the population. The national planning policy during 1945–1965 reflected the national objectives of general economic recovery and improvement of the housing stock. In 1965 the Physical Planning Act came into force, and in 1966 a second National Statement on Physical Planning was issued. National physical planning is accommodated by a system of structure schemes and structure outlines. Economic prosperity in the 1960s led to the general acceptance of economic, physical and sociocultural planning as three equivalent facets of government planning, providing overall direction for a number of smaller-scale sectoral planning processes.