[en] Complete text of publication follows: These proceedings contain the papers presented at the 4-day symposium on Microstructural Processes in Irradiated Materials (MPIM) held in San Antonio, Texas, USA on March 3-7, 2013 as part of the 2013 TMS Annual Meeting and Exhibition. The 2013 MPIM symposium was proposed for a wide range of topics involving nuclear structural and fuel materials to reflect the growing nuclear materials area. The symposium was the sixth in a series of symposia that have been held in the TMS Annual Meeting every two years since the first symposium on March 2-6, 2003 in San Diego, California. The majority of the original contributions to this symposium focused on the experimental and modeling studies on defect production processes in irradiation, radiation-induced phase stability and precipitation, mechanical behaviors, and materials processing. The topics on radiation damage processes in nuclear fuels and fuel related materials and irradiation performance of non-metallic materials and fusion materials have become important components of the symposium. The statistics from the contributed abstracts indicated that the high-chromium ferritic-martensitic steels and advanced ODS ferritic alloys are the most studied materials in a variety of topics, followed by the traditional pressurized water reactor materials such as micro-alloyed ferritic reactor pressure vessel steels and austenitic stainless steels. Other well studied materials include nuclear fuel-related materials, such as oxides, uranium alloys, and Zr-alloys, and fusion materials, such as tungsten and silicon carbide. As in the earlier symposia, a strong emphasis was on the connections between the results of modeling studies on point defects, impurity behaviors, damage accumulation and those of advanced experimental characterization for the microstructural evolution in irradiated or processed materials. The MPIM symposium set new records in the numbers of presentations, with a total of 116 presentations, including 83 oral presentations in 8 sessions and 33 posters in the general poster session. Included among the oral presentations were 14 invited talks from representative nuclear materials areas. After a year-long review process 17 papers have been finally accepted and included in this special issue. (authors)