From the 8th to the 10th century AD, Greek scientific and philosophical works were translated wholesale into Arabic. This activity, whose significance is matched only by the later and related translation of Arabic and Greek works into Latin, resulted in the incorporation and reorganization of the classical heritage in the new civilization, based on Arabic, that spread with Islam. In the past 100 years, editions of Arabic translations of Greek works, often accompanied by Graeco-Arabic glossaries, were the principal means by which the study of this subject was conducted. The Glossarium Graeco-Arabicum is a systematic attempt to present in an analytical and rationalized way our knowledge of the vocabulary of the translations. It is based on the glossaries included in text editions, both published and unpublished, and on other materials gleaned from various sources. The entries are arranged by Arabic roots, and within these by their derivatives as they appear in the sources. Each entry lists the Greek equivalents along with their English definitions, and provides evidence for the use and translation of the word concerned in the form of context citations from both the Greek and Arabic sources. It also includes details on textual variants for the passages cited and complete references to the texts and secondary literature. The work is published in fascicles of 128 pages of lexical entries plus indexes of the Greek-Arabic correspondences, of Greek proper names and transliterated words, of variant Greek and Arabic passages, and of the Greek authors cited in the context passages. From the second fascicle onwards the indexes will be cumulative.