This book presents a number of existing essays as an assemblage of theory on interior design. The approach recognises the complexity of the term 'interior' as it describes spatial differentiation of physical place, and the psychological space of the unconscious. It presents social and political readings conditioned by gender theory, geography, anthropology and cultural criticism, each read against various material conditions of interior design. The book is structured as a matrix with essays organised by two sets. The horizontal set represents the material space of interiors - surface, furnishing, decoration, colour, lighting, and space, while the vertical set lists disciplinary territory upon which the essay reflects: sociology, politics, gender studies, philosophy, psychology, geography and anthropology. Such a matrix offers the potential to not only cross over and between disciplinary boundaries but as well, to survey the multiple threads at play in fabricating interior theory.