This volume collects the proceedings of the 11th International Workshop on Multimedia Information Systems, MIS 2005, which was held during September 19-21, 2005 in the beautiful town of Sorrento, Italy. The MIS series of workshops started in 1995 with the aim of fostering - terdisciplinary discussions and research in all aspects of multimedia information systems, in all their diversity. Since then, in MIS workshops,issues ranging from fundamental multimedia information management research to advanced app- cations in multimedia systems related ?elds have been discussed, new systems have been reported, and the lessons learned have provided new insights into this dynamic and exciting area of computer science and engineering. As the program chairs of the MIS 2005 workshop, we note that while desi- ing an e?ective multimedia system, two complementary issues have to be taken into account: (a) the need to use appropriate technologies in acquiring, p- cessing, and delivering multimedia data which manifest themselves under very di?erent shapes; and (b) the need for modeling, indexing, querying, retrieving, mining, and visualizing data under di?erent system and device capabilities, for di?erent users. Therefore, besides the development of more traditional content management technologies, there are emerging needs to gather media from se- ing devices in the environmental context, for informedprocessingofmediabased on the current task and resources, and for making the results available to the user in the most suitable form based on the capabilities and preferences of the user.