This article gives a survey of results of research concerning effects of public policy in the Netherlands. This survey is preceded by a summary of some important American projects (Equality of Educational Opportunity, Head Start, the Negative income tax). The Dutch research reported concerns effects of educational and housing policy on income distribution, effects of sururbanization policy, participation policy, and still other policies. In both countries the dominant conclusion is that the goals of public policy are at least partially realized by the means chosen. However, the conclusion that the welf are state is totally failing would go to far. Research concerning effects of public policy is still rare. Moreover, it is clear that some goals are realized at least in part by the chosen means. When public policy appears not to be effective, this can be explained from several factors: the contents of policy and the underlying theory, the policy process, the society, the research, and a view which is toonarrow because it takes only short term effects of one particular policy program into account.