Material Evidence in Incunabula (MEI) is a database specifically designed to record and search the material evidence (or copy specific, post-production evidence and provenance information) of 15th-century printed books: ownership, decoration, binding, manuscript annotations, stamps, prices, etc. Developed as a research tool that frames the international program 15cBOOKTRADE, MEI operates under the auspices of the Consortium of European Research Libraries (CERL). It is constantly updated and supplemented by librarians and researchers in more than 450 libraries in Europe and the United States. MEI is linked to the Incunabula Short Title Catalogue (ISTC), provided by the British Library, from which it derives the bibliographical records, and it allows the user to combine searches of bibliographical records (extracted from ISTC) with copy specific records.

Personal and institutional names of ownership are collected in the satellite database Owners of Incunabula, where further bio-bibliographical information can be found. This provides links to all the copies owned by the same person or institution, allowing for the reconstruction of dispersed collections. Provenance locations are also linked to another satellite database Geographic Regions, which offers geocoordinates and map locations. Finally, the database Holding Institutions contains the names of the libraries listed in MEI and ISTC. In MEI we are also capturing evidence of specific copies known to have existed at a certain time in a certain place, from documentary evidence, and now lost.

MEI has been developed to provide a physical representation of the circulation of books throughout the centuries, from place of production, to their present locations. The visualisation tool 15cV is currently unavailable. In February 2021, a map showing the location of collections of incunabula recorded in MEI was set up.