This contribution discusses the phenomenon of improvisation from the perspective of the sociological theory of action and interaction. It postulates that the notion of action, frequently accepted within the theory and defined as either planned or routinized conduct, is not adequate to explain phenomena like improvisation processes. Hence, the notion of “musical material” is postulated as one of the central elements to elucidate improvisation, together with the interaction and the communication medium employed. The article proposes to understand the musical material as sedimented knowledge that is generated, transformed and adapted in the moment and the situation of improvisation. This enables us to explain not only the routine dimension of action and interaction, but also its creativeand spontaneous aspects.Keywords:Improvisation, creativity, action theory, interaction, material.