Posidonius was a major intellectual figure of the Hellenistic world whose interests and contribution spread over the whole intellectual field: philosophy, history, the sciences. His writings are of interest not only to philosophers and classicists, but also to historians and history of science. His work survives only in fragments. The text of these fragments, collected and edited by L. Edelstein and I. G. Kidd, was published in 1972 (Vol. I The Fragments), with a second edition in 1989. This collection, along with Vol. II The Commentary by I.G. Kidd (1988), has become established as the definitive modern edition. However, many of the fragments are extremely difficult to translate, and this volume of translations has been compiled to make this interesting material more easily accessible to scholars and students. The translations are accompanied by contextual introductions and explanatory notes where necessary. An Introduction summarises the importance of Posidonius and his work.