Abstract. There are a number of different criteria for measuring the success of plans in planning. In the planning literature there is a debate about the criterion of conformance (that is, whether spatial development is according to plan) as opposed to performance (that is, whether the plan has shown the way to better decisionmaking), which is, in fact, different from performance measurement. In this paper both criteria are applied to measure the success of Dutch national concentration policies in the``Fourth Memorandum on Spatial PlanningöPlus''. The author shows that the urban containment policies conform well to the plan but perform badly in terms of improving current decisionmaking on the stagnation of housing production in the Netherlands. Moreover, the present stagnation of housing production is planned stagnation. With this result, the author shows that conformance and performance are independent criteria for measuring planning success, and that plans (as set out in the``Fourth Memorandum on Spatial PlanningöPlus'') with high conformance may still perform badly on the performance criterion.