Jaakko Tahkokallio is a Senior Researcher at the National Library of Finland where he leads the ERC StG project Books of the Medieval Parish Church (2021–2025). He also teaches history of the book and palaeography at the University of Helsinki and supervises graduate and postgraduate work on medieval manuscripts.

Tahkokallio’s research concentrates on high- and late-medieval manuscript culture. His doctoral dissertation was on the manuscript reception of Geoffrey of Monmouth’s History of the Kings of Britain, a topic on which he has thence published several articles. He has also published a short OA monograph on Geoffrey of Monmouth and his contemporaries William of Malmesbury and Henry of Huntingdon. Currently he is pursuing research into the fragment collections of the National Library and Riksarkivet (Stockholm).

Other themes of Tahkokallio’s interest are the use of Classical Latin texts in the Middle Ages and long-term developments in the modes of production of manuscript books. In his study of these topics, Tahkokallio has developed and applied quantitative methods besides traditional palaeographical approaches.

Tahkokallio has also worked as an information specialist in the Special Collections in the National Library, and he is still involved in curatorial tasks in a small way. Tahkokallio's main areas of responsibility in the Library have been the Nordenskiöld Collection of maps and geographic literature, early European prints, the medieval fragments and various forms of outreach.

Previously, Tahkokallio has worked as a post-doctoral researcher at King’s College (2014-2015), London and University of Helsinki (2013-2014). During 2018, he spent a research leave as a researcher in an ERC-funded project Medieval Publishing (PI: Samu Niskanen, University of Helsinki).