The aim of this talk is to outline a genealogy of the concept of Lebensraum. I will focus on the way that Darwinian evolutionary thought was translated into 19th Century German geography, particularly in the work of Friedrich Ratzel and his formulation of the concept of Lebensraum. I argue that the Ratzelian Lebensraum must be viewed as a concept aimed towards a synthesis between biogeography and anthropogeography. I will also trace how the Ratzelian Lebensraum came to play a vital part in Rudolf Kjellén's later formulation of an organic theory of the state. Here the talk will focus specifically on Kjellén's organic taxonomy of the political system. I will end with a short discussion on the synthetic aspects of the Lebensraum concept, focusing on the seemingly divergent ways that the Lebensraum concept was mobilised within National socialist ideology and planning.