Mixed economies are characterized by an extensive legislative structure. However, a distinction should be drawn between the extent of the formal planning structure and the functional effects. In this research the functional planning role of government is evaluated in relation to residential developments in the metropolitan region of the Dutch Randstad. In using cluster-analysis the spatial development of this region during the period 1960-80 is traced. The outcome points to a spatial heterogeneity of residential areas. A confrontation of these findings with spatial policies shows the ineffectiveness of the latter because of lagging policy instruments, changing aims and a lack of coherence between various policy levels. Moreover, the situational perception by the government and the complexity of the system of the metropolitan region shows to be detrimental to the steering capacity of spatial policy.