The course of History and Theory of the Interior Design combines the most significant chapters of the transformation of the interior design since the end of the XVIII century with a comprehensive theory of interior design from a wide and international perspective. The course, mainly theoretical, is organized with ex cathedra lectures on the history and methodology of the project and brief insights on case studies. According with a chronological and thematic approach, the lessons illustrate and analyse works, protagonists, architects and designers, writings and drawings, especially focusing on the domestic space. Explicit reference will also be made to the exhibition, retail, work and public spaces as different functional types. The course aims to provide cultural and theoretical tools for a holistic view of the interior design, with specific attention to the connections between the transformation of the interior spaces and diverse factors, such as the cultural and socio-political conditions, local environmental factors and the innovation of techniques. The part relating to the history of interior design includes a chronological arc that goes from the Second Industrial Revolution to nowadays and illustrates examples of interior design by relating architecture, furnishings, equipment, social and custom changes and productive ways to infer the different ways of living the space that have taken place diachronically. The theory of interior architecture is intertwined with the history of architecture with the same chronology, illustrating the proposals for the construction of an autonomous theoretical corpus. The specificities of the interior design will not be limited to the evolution of taste and lifestyles but will specifically focus on the wellbeing of people. These concepts will be presented to students with reference to the design tools, the themes and the key concepts that characterize the interior design.