The seminar will present results from a study assessing the associations between healthcare outsourcing to for-profit providers and treatable mortality rates in England. Debates about the impact of outsourcing healthcare services on quality of care have been high-profile in the public discourse. However, evidence on the impacts of outsourcing has been difficult to produce because comparing health outcomes for patients in different providers does not compare like-for-like while aggregate data on outsourcing has previously been difficult to harmonise. The research resolves this by utilising a novel data resource which has harmonised over 12,000 individual data files with commissioner expenditures totalling over £200bn in NHS spend. We observe a consistent increase in outsourcing to for-profit companies between 2013 and 2020 and find that increases in outsourcing are associated with increases in treatable mortality rates in the following year. From these results we suggest that outsourcing of services corresponds with declining quality of healthcare.