In the context of acquiring, exhibiting and lending cultural heritage objects, libraries set out to legally and ethically do the right thing. In this workshop we will explore how we can ensure such a legal and ethical approach through the application of due diligence and provenance research, and how relevant workflows and policies can be established. Together we will explore the potential tension between ‘legal’ and ‘ethical’, how the provenance of some items in our collection may make them unsuitable for display or lending, and what impact libraries’ research into the origins of cultural heritage objects may have on libraries’ relationships with donors, the book trade, and other libraries in their country.