This paper reports on the compositional processes of an Italian rock band whilst composing a new piece over seven group composing sessions. The band members were videotaped during the group composing sessions in their rehearsal room. A qualitative analysis of the video recordings was performed using the Constant Comparative Method. In the analysis, 59 different behaviours emerged, which were subsequently reduced into 13 categories. When analysing the categories, five themes (activities) were defined. The five activities were: context definition, experimenting, constructing, playing and evaluating. The activities were employed as a coding technique for time coding the videotaped data, which revealed the time percentages spent by the musicians in each of the group composing activities. Results from the joint qualitative and percentage time analysis indicate the importance of the strategies adopted by the musicians during group composing. The results are discussed by taking into account the impact of the processes employed in a group composing setting as well as suggestions for future research. The implication for music education involves the possibility to apply approaches based on the development of cognitive processes rather than the product of collaborative composing activities.