The Ars edendi Research Programme, funded by Riksbankens Jubileumsfond and based at Stockholm University, explores both theoretical and practical issues of the editing of medieval Greek and Latin texts, especially in genres presenting quandaries to standard error-based, Lachmannian approaches. Since the start of the eight-year programme in 2008, the series of Ars edendi lectures has given experienced textual scholars the opportunity to share their perspectives on current developments in textual criticism or to address specific editorial challenges. This volume offers the reflections and experiences of two Latin and two Greek scholars as well as the perspectives of a researcher in library and information science concerning critical digitization. Mats Dahlström contrasts ‘mass digitization’ with ‘critical digitization’, and discusses the advantages of both, as well as touching on other fundamental issues involving library digitization and scholarly editing. Michael Winterbottom discusses how an editor may proceed when there is evidence of rewriting, which the classical scholar can only rarely determine has taken place, whereas the medieval scholar can sometimes get right back to the top of a tradition and ‘see the goal posts moving, and know or guess who was moving them.’ John M. Duffy offers illustrations of the commonsensical ways of retrieving and restoring the text in the case of Sophronius of Jerusalem, where the editor has the advantage of the author’s attachment to rhythmical prose. Tiziano Dorandi assesses the value of parallel Byzantine traditions from the perspective of an editor of Diogenes Laertius, and asserts that the editor must avoid falling into the trap of mixing traditions. Frank Coulson discusses the editorial problems peculiar to medieval commentaries and glosses on classical authors, concentrating on the commentaries to the Metamorphoses of Ovid.