This paper explores firstly the sense in which improvisation might be conceived of as an informal music education process and, secondly, the effects of a course in free improvisation on student teachers' perceptions in relation to themselves as musicians, music as a school subject and children as musicians. The results of a study conducted in two Greek universities are presented. Using a narrative methodology, examples of data from the reflective diaries or learning journals which 91 trainee teachers kept as part of their participation in an improvisation module are presented and discussed. The argument is made that improvisation, as a particular type of informal music learning process, has an important role to play in fostering the qualities required of teachers to work with informal pedagogies in music education. Furthermore, we would suggest that such musical experiences might gradually lead to the development of a critical perspective on both music education theories and practices. Improvisation might emerge as a moment and a practice of rupture with linearity of progress, working against reification of knowledge and glorification of received information. The findings suggest that improvisation might offer a route for creating an intimate, powerful, evolving dialogue between students' identities as learners, their attitudes towards children and their creative potential, and the interrelationships of the notions of expressive technique and culture, thus becoming "an act of transcendence" (Allsup, 1997, p. 81). We propose that the issue of connecting informal learning and improvisation might be resolved by regarding improvisation as an exemplary case of creating a communicative context where most representations/conceptualisations/struggles to solve problems are left implicit. Such experiences for pupils and teachers alike might further extend the social and personal effectiveness of informal learning as music pedagogy.