In my thesis, I examine how German jurists, beginning with Carl Friedrich Savigny, at the dawn of the 19th century, to Rudolf von Jhering, towards the end of it, interpreted the Roman sources on possessio, thus, constructing the German concept of possession (Besitz); a development that was to be adopted by the two major civil codifications of the German-speaking world, namely the Austrian ABGB and the German BGB. Influenced by German idealism, notably the views of Kant, but also driven by contemporary considerations regarding the place and usefulness of Roman law in the German-speaking countries, leading German jurists of the nineteenth century radically pursued a new approach towards Roman sources and simultaneously informed their interpretation with notions of German idealism, while always pledging their faith towards the historical material. This motley group included noted jurists like Puchta, Keller, Windscheid, Brinz, Bekker, Kuntze, Dernburg, Loehr, Huschke, Sintenis, Arndts, Böcking, Bethman-Hollweg, Regelsberger and Unger. They called themselves members of the 'Historical school' because they believed it to be their task to trace Roman law back to its classical roots, by 'cleaning it' from 'medieval contamination.' I also included Rudolf von Jhering in my discussion because he holds an ambiguous position, he is both considered part of the 'Historical School' and its opponent. Since they all looked at Savigny as the founder of their school, it comes as no surprise that the scholars all reacted in various ways to Savigny's seminal monograph on possession Das Recht des Besitzes, which appeared in six editions with slight modifications from 1801 to 1836. In my examination, I draw on a limited circle of jurists that participated in the debate on possession, but I also include scholars who were not considered as part of the group, such as Maximilian Theodor Zachariä, but who engaged with the group extensively on the matter of possession. In my treatment of the discussion of the concept of possession and possessory interdicts (interdicta possessionis), I trace the different lines of thought of various members of the 'Historical School.' I compare the points where they agree, or disagree and, I am trying to trace their influence on others, and eventually on the German civil code, the Bürgerliches Gesetzbuch. My treatment will show that the 'Historical School' was not as homogenous as it is often assumed even today day. For this, the movement must be placed in its historical context. The rising citizen class in Germany would seek to terminate the old feudal order in Germany, which represented an agrarian, land-based economy, and society. For this aim, they needed a different private law, namely, one that perceived both the contract and ownership as central. This becomes obvious when we compare the Preußisches Allgemeines Landrecht of 1794, or the Austrian civil code, of 1812 though enlightened codes, still preserving the old feudal order with different degrees of possession and ownership (Gewere), with the Bürgerliches Gesetzbuch of 1900, which was strongly influenced by Savigny and his disciples. I will dispute the commonly held notion that 'Pandektists' tried to mould Roman law, which was perceived as casuistic and not systematic, into a theoretic, abstract one by showing that, on the one hand, 'Pandektists' themselves were less prone to abstracting as Jhering held them to be, and, on the other, that Jhering himself might be more given to theorizing than he would have us believe he did, thus, Jhering cannot be seen as the antipode of the 'Historical School' but his contribution to the discussion of possession is seminal as we will see. In discussing the treatment of possessio, I will examine two separate questions, namely, how possession is created, and why is it protected? These two questions are often intermingled in the argument, but a crucial as they live on in both the German and Austrian civil codifications (Possessorischer Besitzschutz, §859 BGB, petitorischer Besitzschutz, §1007 BGB; §372ff ABGB), and only the latter goes back to the Roman sources, (actio publiciana). The debate on the nature of possession, and its ramifications, ushered in by Savigny, and continued by followers and opponents, still informs the legal discourse in Germany and Austria today. I leave the Latin word possessio untranslated throughout my work and render only the German Besitz as 'possession' since possessio and possession are often false friends. I also left the term detentio untranslated. I either quote it in its Latin form or as the German rendition Detention, I do this because the English 'detention' does not render the meaning of either the Latin or the German. The term 'detentor' is equally problematic as it is rendered as 'Inhaber' in the Austrian civil code and can include the possession of rights. In the German civil code, the 'Inhaber' is strictly separated from the possessor; the former referring to a holder of rights, the latter only to a holder of physical objects.