How can music change our mood and induce positive effects? The 9th International Symposium on Computer Music Modeling and Retrieval (CMMR) Music and Emotions took place at Queen Mary University of London on 19-22 June 2012. Jointly organised by the Centre for Digital Music and the CNRS Laboratoire de Mècanique et d'Acoustique (France), CMMR 2012 welcomed researchers, educators, librarians, (film) music composers, performers, music software developers, members of industry, and others with an interest in computer music modeling, retrieval, analysis, and synthesis for what was a great and cutting edge event. For more information go to http://cmmr2012.eecs.qmul.ac.uk.