The delay and lack of progress in implementing large-scale urban housing projects indicate the existence of fundamental obstacles and problems, which seriously threaten the reconstruction and development of urban spaces and can be described as a crisis in construction projects. In this regard, the present study, with a diagnostic approach, seeks to identify the obstacles to the progress of mass housing projects in Iran by presenting a model. Methodologically, this research is qualitative in nature and based on grounded theory. The participants are experts in the field of mass housing projects, of whom 30 were purposefully selected until theoretical saturation was achieved. The data were collected through semi-structured interviews, and the data analysis was conducted using the three coding processes of open, axial, and selective coding. The findings revealed the obstacles to the progress of mass housing projects in six main categories, twelve subcategories, and sixty-nine indicators, including physical–environmental, economic–financial, cultural–social, institutional–managerial, technical–legal, and location–infrastructure barriers, identified based on logic and their interrelationships. Therefore, it seems that by addressing these obstacles, the authorities of mass housing projects in the country can create the conditions for reducing delays in the progress of urban mass housing projects through their planning and policies.