It has been claimed by politicians as well as researchers that economic openness poses a threat to the welfare state. This article investigates whether there is such a threat. Based on the literature four different hypotheses are distinguished; economic openness is negatively, positively, curvilinear or not related to the welfare state. The first and the third hypothesis state that economic openness does threaten the welfare state, whereas the other two hypotheses argue that this is not the case. The empirical studies investigating the relationship between economic openness and the welfare state are systematically reviewed in this article. The analysis shows that economic openness does not threaten the welfare state.