Changes in governments are generally accompanied by the formulation of new policies and transformations in the political, social, and cultural spheres, and these changes may be reflected in social structures and housing architecture. From this perspective, settlement patterns and architectural organization develop over time through an interaction between governmental policies and social conditions. Anthony Giddens’s theory of structuration, emphasizing the reciprocal relationship between structure and agency, views social transformations as resulting from the interaction between structural conditions and social actions, thereby providing a framework for simultaneously analyzing the roles of structures and social activists. Drawing on this theoretical framework, the present study examines the transformations of the housing architectural system in the city of Ilam from the Qajar period to the First Pahlavi period. The aim of the research is to identify and analyze the patterns of the architectural and spatial systems of housing in the two periods and to examine their relationship with changes in governmental policies within their historical context. The research adopts a mixed-methods approach, combining qualitative and quantitative ones. In the first stage, library and documentary studies were conducted to examine Giddens’s theory of structuration, governmental policies related to sedentarization and settlement, and the characteristics of the housing architectural system in Ilam. Subsequently, the architectural and spatial elements of housing in the two periods were analyzed comparatively based on six indicators: landscape system, social system, geometric system, spatial system, activity system, and arrangement system. The results indicate that changes in structural conditions and governmental policies are more clearly reflected in certain physical characteristics of housing, particularly in the landscape and geometric systems. In contrast, in the social and spatial layers of architecture, including the social, spatial, activity, and arrangement systems, some spatial and functional relationships associated with culture, lifestyle, and social patterns have shown relative continuity. Therefore, the transformation of housing in Ilam can be understood not as a complete rupture, but as a process involving change, continuity, and adaptation of physical and social patterns in response to structural conditions.