The increasing demand for residential and activity space has made the use and building rights the most valuable resource, and has greatly increased the competition between landowners, developers and public agencies to acquire this resource in the city. In this regard, this article seeks to identify the hidden causal powers and generative mechanisms of determining and allocating land development rights in Tehran. In this article, after systematic reviewing the literature on rights and property rights in spatial planning and with multiple qualitative methodology based on Critical Realism, a data analysis framework was developed that used critical grounded theory as a coding strategy, and retroduction to identify and analyze the causal powers and generative mechanisms of determining and allocating land development rights and duties in Tehran. The data was collected by conducting 23 semi-structured interviews and reviewing the 138 documents.In the first cycle of coding, 723 preliminary codes were extracted from the interviews and 335 preliminary codes were extracted from the documents. In the second cycle of coding by combining the extracted codes from the two sources and in an iterative process and continuous comparison, the codes were analysed and finally subcategories and categories were extracted. And then in retroduction analysis and coding phase, the relationship between categories and subcategories was checked and generative mechanisms and causal powers were identified.
The results show that the determination and allocation of land development rights and duties in Tehran is the outcome of the interaction of contextual, structural, discursive, institutional and agential causal powers and related generative mechanisms. These interactions within the planning system, in its institutional environment and the context of Tehran, has formed the " Tehran's land development rights regime" that its output is the production of space.