This research aims to investigate the use of post-graduate theses in library and information science in Isfahan libraries. Research populations consist of 26 managers and librarians and 54 theses and dissertations. Sampling was not considered. Semi-structured interviews were carried out. The technique of continual comparison proposed by Grounded Theory methodology was used for analysis of data.12 categories were explored. Use was the basic category.Other categories identified include: recognition, information and communication system, management, content and structure of theses, legal, organizational, and financial support issues. Each category influences the use. Research priorities also affect the use. Relationships among categories were found to be direct, indirect, and combined.Findings showed that suggestions and results in theses are not used in libraries investigated. Managers proposed the following as barriers: weakness of information and communication channels, weakness of management systems, legal issues, cultural, financial, organizational, and professional problems and problems related to content and structure of theses.