This paper reports on a qualitative investigation of explanations for teenage girls' indirect aggression (e.g., spreading false rumours, excluding peers from the group) which is part of a larger study on the nature of teenage girls' indirect aggression. Focus groups were conducted with fifty-four 15–16-year-old girls. These focus group data were supplemented with interviews with six pairs of girls and a focus group discussion with a pilot group of eight 16-year-olds and separate individual interviews with ten key teachers. The overall aim of this part of the study was to explore why girls are indirectly aggressive to their peers. The key explanations proposed by the girls and their teachers were a desire to create excitement in girls' lives together with a range of friendship and group processes, centred around having close intimate relationships and belonging to the peer group. This study enriches our understanding of girls' indirect aggression and adds to earlier research conducted mainly using quantitative methods.