In the Dutch welfare state social policy research always has been an essential tool in policy development. Much public money has been spent on explanatory research and research that has to be supportive to policy design, policy improvement and the evaluation of social policies. A significant field in this respect is social security and more in particular the Dutch disability problem. Since the onset of the at the time fundamentally changed public disability insurance legislation in the second half of the sixties of the last century, disability has become one of the biggest problems of the Dutch working population. The number of disabled workers increased rapidly after the introduction of the Disability Insurance Act (WAO) in 1967 from about 200.000 to almost one million in the nineties (about 10% of the whole Dutch working population) and remained at this unusual high level until today. To be able to tackle this problem Government and the administrative organizations carried out and funded several hundreds of research projects since the seventies. In this paper we investigate the impact of this research on policy-making. The main question to be answered is to what extent the results of research have been used in policy-making regarding the WAO. On the basis of three more specific case studies we conclude that this impact has been very modest. More in particular, by means of detailed document studies and complementary interviews with the relevant stakeholders we investigated three important and far-reaching corrective legal reforms in the nineties and the role policy research played in this respect. Various aspects explain the under-utilization of research, but one of the most important ones is the complicated political context in the Netherlands. Many institutional actors, that are interdependent and locked into permanent negotiation over such a sensitive societal issue, are involved. Therefore, consensus on the basis of particular research results or recommendations is difficult to envision.This paper has ...