Supplementum Grammaticum Graecum is an essential reference work for scholars of Greek antiquity, designed to complement Jacoby Online and specifically Die Fragmente der Griechischen Historiker IV. It is a collection of critical editions of testimonies and fragments of Greek grammarians, namely, ancient scholars dealing with textual criticism, literary exegesis, grammar, biography, and the various fields of erudition.

Each entry consists of a biographical and cultural profile of a grammarian and a new (often first) critical edition of all the existing testimonies and sources in their original language. These are supported by translations and analytical commentaries and followed by a thorough bibliography and indices.

The project is overseen by general editors Franco Montanari, Fausto Montana, and Lara Pagani, whose expertise ensures the scholarly precision, rigor and reliability of this resource.