This chapter presents new, annotated translations of the testimonia and fragments of the much-travelled Poseidonios of Apameia (c.135–c.51 BC), selected for their geographical content and arranged as 75 extracts. (Translations of passages of Strabo are adapted with permission from the work of D. W. Roller, and a lengthy passage of Priscianus Lydus from the translation by I. G. Kidd.) The chapter introduction notes the bias introduced into our understanding of Poseidonios’ geography by the particular interests of Strabo and Athenaios, the commonest sources of extracts; and demonstrates Poseidonios’ achievement in integrating cosmology, philosophy, and geographical thought. Prominent advances made by his writing are in areas such as the tides, climatic zones, and the interaction of humankind with the natural environment.