Abstract-According to the Scrum process framework a Scrum team should have all necessary competencies to accomplish its work. Fragmented and anecdotal evidence hints at Scrum teams still needing additional, external competencies. To contribute to theories on Scrum team composition and practitioner's concerns in staffing a Scrum team we investigated Scrum teams' cross-functionality: To whom do Scrum teams turn for additional competencies, which competencies are involved and how are Scrum teams aware of additional competencies they need? To this extent we analysed the communication in three Scrum teams during one of their Sprints. Our results show that additional competencies are called for, not only on an ad hoc basis, but also on a structural basis. To include those structural competencies the notion of an extended Scrum team is introduced.