During the past 30 years, the Mismatch Negativity (MMN) event related brain potential (ERP) has become one of the prime electrophysiological tools in studying perception, memory, and attention, as well as high level cognitive processes, such as understanding speech and music. As a consequence, the development and modeling of MMN and applications of MMN for detecting and monitoring cerebral and psychological dysfunctions have also received increasing attention. The series of meetings, which started in Helsinki in 1998, with the most recent one held in Cambridge in 2006 have successfully covered the ever widening range of research topics the study of which has benefited from the use of the MMN method (see the Table of Contents of the Special MMN Issue of the Journal of Psychophysiology created from presentations at the Cambridge meeting) The upcoming meeting in 2009 in Budapest, organized by the Institute for Psychology, Hungarian Academy of Sciences will aim at continuing this tradition. We wish to provide a forum for presenting new results and theories and for discussing all aspects of neuroscience and psychology, clinical as well as basic research, to which MMN studies contributed. We also wish to keep the meeting especially accessible to students.