The main question of this article is: Which methods ofdesigning a policy are fit to solve or diminish complex and certain, complex and uncertain, simple and certain, simple and uncertain policy problems? On the basis of a contingency approach hypotheses are formulated with regard to this question. These hypotheses are confronted with the field of Dutch municipal policies for marginal adolescents (in the period 1980-1990). This study intends to point out: - that a diagnosis-modelfor designing a policy is appropriate to tackle complex and certain problems; - that a learning-model for designing a policy is appropriate to tackle complex and uncertain problems; - that a fitting policy theory is a necessary, but insufficient condition for an effective policy; - that a lack ofconsensus in the political environment of the process of designing a policy has a negative effect on the goal attainment, if the opponents of the policy have the power to obstruct the process of implementation; - that a lack professional qualities of implementers has a negative effect on the goal attainment.