Music in Groups happens all the time: in the street, the classroom, in music colleges, community centres, hospitals, prisons, churches and concert halls; at raves, weddings, music festivals, public ceremonies, music therapy sessions, group music lessons, concerts and rehearsals. Some group musicking seems to 'work' (and play) better than others; some sessions feel exhausting even if things are going well; and at other times, we can't begin...