An episode of two students working collaboratively on a mathematical problem is analysed combining two approaches, namely the process model for mathematical level raising and role theory. The process model stresses the importance of key and regulating activities, while role theory deals with the inter- and intrapersonal concerns of the participants. Our results show a connection between these activities and particular participants' roles: depending on their own definition of the ongoing situation the students are engaged in more or less key and regulating activities, which in turn affect their mathematical level raising.