In order to establish a causal claim, one needs to establish both that the putative cause and effect are correlated and that there is a mechanism linking the former to the latter that can explain this correlation. This evidential pluralism thesis has led to some very fruitful work in the philosophy of the biomedical sciences and to suggestions for improvements to evidence-based medicine. This project will investigate whether the thesis also applies to the social sciences. Can it be used to provide foundations for ‘mixed methods research’ in the social sciences? Can it lead to improvements in evidence-based social policy?