This paper describes what improvising came to mean to a group of 12-year-old children who, as members of a weekly lunchtime ‘Music Creators' Soundings Club’, were watched, listened to, and invited to reflect upon the process of group improvisation. Focusing on musical interaction as it emerged in the earliest stages of this work, this paper shows the relationship between children's actions and their reflective talk. It identifies emerging principles in a sequence of musical examples that portray children making music together and shows the nature of group improvisation as socially and musically inclusive. These children valued group improvisation most for its immediacy and continuity. Ways of delighting in how children behave musically and reveal their musical learning through conversation are discussed.