This issue of Organised Sound is about interactivity, a theme that the journal has often visited in the past. What makes this visit to this very important subject special is that it has been chosen as the first theme within our annual collaboration with the International Computer Music Association (ICMA). The ICMA President, Mary Simoni, has joined the Editors this year as ICMA representative and Mara Helmuth, currently the ICMA's editor of Array, has kindly taken on the role of Guest Editor for this issue. The journal Editors would like to welcome the ICMA and thank those ICMA members, and Mara in particular, who helped to make this issue possible. We look forward to further developing this collaborotion.