By re-examining French geographer Pierre Gourou's work, this book highlights the significant (yet only partially understood) role he played in shaping how the tropical world was viewed during the 20th century. It does so by connecting Gourou to the idea of 'tropicality' - a discourse which constructs 'the tropics' as the West's environmental Other (in both positive and negative terms - as exotic, Edenic and bounteous, but also as backward, debilitating and pestilential). While Gourou had a towering influence over French geography, this is the first book-length study of him, as well as being the most extensive critical and contextual treatment of the geography of tropicality to date. Through its focus on Gourou, it explores how questions of geography (of ontology, epistemology, experience and materiality) enter into the constitution of this discourse and its imperial maps of meaning. During a long career spanning eight decades which took him to many different parts of the world, Gourou's attempt to explain and interpret 'the nature' of the tropical world is best conceived as a series of projects and experiments in investing 'the tropical' with meanings that were built on the shifting sands of world affairs and that operated in a lateral relationship with dominant and competing 20th-century discourses - of modernity and disenchantment, war and revolution, culture and civilisation, empire and freedom, and race and development. In addressing key questions about the location and power of knowledge, this book argues that Gourou should be regarded as a leitmotif of a more general (constitutive) ambivalence in the make-up of tropicality and its manipulation of meaning.